The data deposited consists of interview transcripts (with identifying information obscured) from two samples of intact couples, the collection of which was made possible by the secondment of the Knowledge Exchange Fellow, Jan Ewing (University of Exeter) to the Relationship Support charity, OnePlusOne. Sample 1 consists of the 24 of 33 married couples interviewed separately but consecutively at year 15 of marriage, who agreed to deposit their data in the UK Data Archive. Ewing recruited the original sample of 52 couples before marriage and interviewed couples four times over the first 10 years of marriage between 2007 and 2017. In 2017, the sample comprised 45 couples; 39 intact and six separated couples). In 2022, 32 intact couples and one couple who separated the previous year agreed to a further interview. In 2017, this sample was complemented by a cross-sectional relationship-diverse sample of a further 10 couples (4 same-sex and 6 different-sex), some of whom were cohabiting (4) or civil partnered (2), and all of whom had lived together for more than 15 years. In 2022, all ten couples (Sample 2) agreed to a further interview and the deposit of the obscured interview data in the UK data archive. The data collection therefore comprises 68 individual interviews from 34 couples, each approximately 20 pages long. The study sought to test longitudinally for the first time and within the context of couples navigating the Covid pandemic, the Relational Capability Framework developed by OnePlusOne drawing on the capability approach of Sen and Nussbaum. Relational capability is the ability to initiate and maintain relationships (internal capability) and the opportunity and the conditions that enable individuals to form and maintain relationships (relational opportunity). As the Fellowship coincided with the country emerging from Covid lockdowns, this enabled an exploration of how intact couples have coped (or not) with the relationship stress caused by Covid compared to other stressful periods they have lived through as a couple (e.g., the financial crash in 2008). In particular, the enforced lockdowns and restrictions to everyday life that the participants had lived under in the period immediately before the project proved a perfect ‘petri dish’ to test the theory of relational opportunity. As hypothesised, both the home and communities in which couples lived and the response from schools, employers, and the government profoundly affected the couple’s experience of Covid and their ability to nurture their relationship at this time of national and personal crisis. Age, life stage, and personality type were also significant moderators of how couples experienced and navigated Covid, underscoring the need for a greater understanding of and nuanced response to couples’ needs at different life stages to optimise the conditions and circumstances in which relationships may flourish. Additionally, the couples who navigated the Covid crisis well tended to be those in which one or both members of the couple were relationally capable, displaying the individual-level skills and attributes required to sustain relationships, such as empathy, flexibility, friendliness, likability, understanding, the ability to see the other’s perspective, and altruism (Mansfield and Reynolds, 2014:4).The project used semi-structured interview methods with two samples of couples in intimate relationships followed longitudinally over a 15-year and a 5-year period respectively to identify what drives thriving relationships across the life course and test the 'Relational Capabilities Framework' model developed by the relationship support charity, OnePlusOne. The data deposited consists of interview transcripts (with identifying information obscured) from two samples of intact couples, the collection of which was made possible by the secondment of the Knowledge Exchange Fellow, Jan Ewing (University of Exeter) to the Relationship Support charity, OnePlusOne. Sample 1 consists of the 24 of 33 married couples interviewed separately but consecutively at year 15 of marriage, who agreed to deposit their data in the UK Data Archive. Ewing recruited the original sample of 52 couples before marriage and interviewed couples four times over the first 10 years of marriage between 2007 and 2017. In 2017, the sample comprised 45 couples; 39 intact and six separated couples). In 2022, 32 intact couples and one couple who separated the previous year agreed to a further interview. In 2017, this sample was complemented by a cross-sectional relationship-diverse sample of a further 10 couples (4 same-sex and 6 different-sex), some of whom were cohabiting (4) or civil partnered (2), and all of whom had lived together for more than 15 years. In 2022, all ten couples (Sample 2) agreed to a further interview and the deposit of the obscured interview data in the UK data archive. The data collection therefore comprises 68 individual interviews from 34 couples, each approximately 20 pages long. The study sought to test longitudinally for the first time and within the context of couples navigating the Covid pandemic, the Relational Capability Framework developed by OnePlusOne drawing on the capability approach of Sen and Nussbaum. Relational capability is the ability to initiate and maintain relationships (internal capability) and the opportunity and the conditions that enable individuals to form and maintain relationships (relational opportunity). As the Fellowship coincided with the country emerging from Covid lockdowns, this enabled an exploration of how intact couples have coped (or not) with the relationship stress caused by Covid compared to other stressful periods they have lived through as a couple (e.g., the financial crash in 2008). In particular, the enforced lockdowns and restrictions to everyday life that the participants had lived under in the period immediately before the project proved a perfect ‘petri dish’ to test the theory of relational opportunity. As hypothesised, both the home and communities in which couples lived and the response from schools, employers, and the government profoundly affected the couple’s experience of Covid and their ability to nurture their relationship at this time of national and personal crisis. Age, life stage, and personality type were also significant moderators of how couples experienced and navigated Covid, underscoring the need for a greater understanding of and nuanced response to couples’ needs at different life stages to optimise the conditions and circumstances in which relationships may flourish. Additionally, the couples who navigated the Covid crisis well tended to be those in which one or both members of the couple were relationally capable, displaying the individual-level skills and attributes required to sustain relationships, such as empathy, flexibility, friendliness, likability, understanding, the ability to see the other’s perspective, and altruism (Mansfield and Reynolds, 2014:4).

To identify what drives thriving relationships across the life course and to test the Relationship Capability Framework longitudinally, we conducted follow up interviews with Ewing’s longitudinal sample of couples married for the first time in 2006/7 (‘Sample 1’). Most of this sample had originally been approached from announcements of intended marriages posted at a local Register Office in the South East (Ewing, 2014), although their places of residence were more geographically spread across England, with one couple now living abroad. These couples had been interviewed separately but consecutively four times over the first ten years of the marriage (at three-six months (time 1), 12-18 months (time 2), three-four years (time 3) and 10 years (time 4)). The sample comprised 53 couples at time 1, 52 couples at time 2, 49 couples at time 3 and 45 couples at time 4 (39 intact couples and the six couples known to have separated at that stage). At time 5, 15 years into the marriage, 33 couples agreed to an interview; 32 intact couples and one separated couple. Two couples withdrew from the process, two could not be traced, one agreed but proved impossible to engage and one spouse had sadly passed away since the last interview. In order to obtain data on couples across a wider demographic (married and unmarried couples in opposite-sex or same-sex relationships) and over a longer time span, at time 4 (2017) we purposively recruited and conducted face-to-face interviews with 10 couples in relationships of at least 15 years’ duration based in South West England (‘Sample 2’). The sample comprised 4 same-sex and 6 different-sex couples, some of whom were cohabiting (4) or civil partnered (2), and all of whom had lived together for more than 15 years. In 2022, all ten Sample 2 couples agreed to a further interview. Previous rounds of data collection had been conducted face to face. However to ensure Covid-safety for both the researcher and participants (many of whom are in more susceptible age ranges), interviews were by Zoom, save for 2 couples who expressed a preference for a telephone interview. The Zoom interviews were audio, but not visually recorded, with the participants consent. All participants were provided with an information sheet and consent form ahead of the interview and informed consent to the interview was obtained mostly by participants completing an online ‘Microsoft Forms’ consent form. Those who had not completed the ‘Microsoft Form’ or a paper copy of the consent form had their consent orally confirmed at the outset of the interview, including whether they consented to deposit of the interview (with identifying details obscured) into the UK Data Archive. The interview data was professionally transcribed, anonymised and then coded using Nvivo 2020 using a codebook co-developed by Ewing and One Plus One using Braun and Clarke’s six phases of thematic analysis and an inductive approach (Braun and Clarke, 2006). Once initial codes had been developed, collated into potential themes and further refined, both Ewing and a researcher from OnePlusOne coded an interview from each sample using the draft codebook. A coding comparison query was conducted in NVivo. Any codes that the coding comparison indicated had a Kappa co-efficiency score of ≤ 0.75 (0.75 and over being considered 'very good', Fleiss et al, 2003) were discussed to agreement and codes refined before coding the remaining interviews. This ensured inter-coder reliability and demonstrated the trustworthiness of the findings. The University of Exeter Ethics Committee approved the project under reference number 493864. The deposited data consists of the interview transcripts (with identifying details obscured) from the 24 ‘Sample 1’ couples and 10 ‘Sample 2’ couples who agreed to the deposit of their interview transcripts into the UK Data Archive (68 interviews in total).