Self-injurious thoughts and behaviors (SITBs), including suicide, thinking about suicide, and self-injury without intent to die, are major public health crises, with variably effective, and sometimes long and expensive, interventions. SITBs are particularly common in borderline personality disorder (BPD). Moreover, people with BPD often cannot access SITB treatment, drop out of them, and may lose their improvements after them. Reducing SITBs in BPD requires innovative interventions that have greater impact and are faster to deliver. SITBs are particularly influenced by emotion dysregulation (i.e., intense, negative emotion and difficulties changing it) and intimate relationship dysfunction, but leading evidence-based SITB interventions typically focus on the former, while neglecting the latter. For other mental health problems, couple treatments result in comparable or better individual outcomes relative to individually-delivered treatments, with added benefits of enhanced intimate relationship functioning. SITB treatment outcomes in BPD could likely be expedited and optimized with a couple intervention that targets emotion dysregulation in a relational context and intimate relationship dysfunction. This project aims to develop, refine, and test a brief SITB intervention delivered conjointly to individuals with BPD and SITBs (i.e., "patients") and their intimate partners (i.e., "partners")- Sage (formerly known as COMPASS (Connecting, Overcoming, and Moving Past Suicide and Self- injury))- that targets both emotion dysregulation and intimate relationship dysfunction to reduce SITBs and BPD symptoms in the short- and long-term. Prior to formal testing in an uncontrolled trial, it is important to solicit preliminary data regarding the clarity, accessibility, safety, tolerability, and efficacy of Sage. This project involves 3 Phases: translating Sage outlines into a manual (Phase 1); refining Sage (Phase 2); and an uncontrolled pilot trial of Sage (Phase 3). In Phase 1, the three stages of Sage will be manualized to focus on (1) developing a conjoint safety plan to reduce SITB risk, (2) reducing emotion dysregulation and intimate relationship dysfunction, and (3) changing patterns that maintain SITBs. In Phase 2, Sage will be delivered to 5-10 patients with BPD and SITBs and their partners (i.e., 5-10 couples) who will provide feedback about whether Sage is clear, helpful, and useable. This feedback will be used to refine the Sage manual. In Phase 3, the investigators will test whether Sage is safe, initially efficacious, and feasible by administering it to 15-20 patients with BPD and SITB and their partners (i.e., 15-20 couples). The investigators will examine whether Sage results in changes in SITBs and BPD symptoms in patients with BPD and SITBs, and SITB risk factors (e.g., emotion dysregulation and intimate relationship dysfunction) in both patients and partners. These outcomes will be measured multiple times per day during treatment using participant's smartphones (i.e., ecological momentary assessment), and interviews/questionnaires administered at the beginning, middle, end, and at 3 months after the intervention. The investigators predict that Sage will reduce SITBs and BPD symptoms in the patient with BPD and SITBs and improve emotion dysregulation and intimate relationship dysfunction in both patients with BPD and SITBs and their partners. This study offers a novel SITB and BPD treatment that directly targets SITBs, BPD symptoms, and the factors that drive them. Its short duration broadens the accessibility of BPD and SITB interventions with the potential to contribute to reducing SITBs and BPD symptoms on a large scale. During this period of social distancing due to COVID-19, Sage will be delivered remotely via secure videoconferencing (Zoom Healthcare). As social distancing restrictions lift, Sage will be delivered in the laboratory.

Inclusion Criteria:

1. Patients have either engaged in 2+ suicidal or non-suicidal self-injurious behaviors in the past two weeks (i.e., chronic and recent SITBs, consistent with previous research evaluating non-suicidal self-injury (Kranzler et al., 2018)), or have severe suicidal ideation as indicated by a score ≥15 on the Beck Scale for Suicidal Ideation (Beck, 1991)
2. Patients also meet diagnostic criteria for BPD
3. Patients are between the ages of 18 and 70 years-old
4. Patients have a romantic partner who is between the ages of 18 and 70 years-old
5. Patient's romantic partner is willing to participate in the study with them

Exclusion Criteria:

1. Past-year severe intimate aggression in their relationship such that participants who endorse any severe physical and/or sexual assault behaviors in the past year will be excluded from the study (Monson et al., 2012; Abramowitz et al., 2013), as assessed by the Revised Conflict Tactics Scale, Severe Items Subscale (CTS-2; Straus, Hamby, Boney-McCoy, & Sugarman, 1996)
2. Either partner has a severe substance use disorder that would interfere with the capacity to attend and participate in this study
3. Either partner has clinically significant psychotic symptoms or bipolar I disorder (e.g., McMain et al., 2018; McMain et al., 2009)
4. Either partner has a major cognitive or intellectual impairment that would prevent the individual's ability to attend intervention and participate in the research study
5. Either partner has illiteracy in English language
6. Either partner is unable or unwilling to download and use a mobile application on their smart phone to complete daily Ecological Momentary Assessment (EMA) measures
7. If partners meet inclusion criterion #1, or #2, or meet the self-harm/suicidal behaviour diagnostic criterion for BPD.
8. If either partner of the couple is unwilling to have assessments and sessions audio or videorecorded
9. If either partner is currently not residing in Ontario