Table 2 Study objectives with associated outcomes and criteria for success of feasibility, hypothesis for secondary outcomes, and methods of analyses

 Recruitment

Number of participants accessed (i.e., initiate registration) per week, stratified by recruitment source

10 couples per week over the course of 4 weeks who access our registration site.

Descriptive statistics

Number of participants enrolled per week, stratified by recruitment source

5 couples per week over the course of 4 weeks who enroll in the study.

 Eligibility criteria

% interested participants that meet the inclusion criteria (with reasons for exclusion)

< 50% of participants are excluded for any one criterion.

 Sample diversity

% participants income ≤ regional median, ≤ high school degree

> 30% of our sample has 1+ indicator.

 Sample diversity (race/ethnicity/immigration)

% participants racialized, immigrant

> 30% of our sample has 1+ indicator.

 Sample diversity (sexual orientation/gender)

% participants non-heterosexual, gender non-conforming

> 30% of our sample has 1+ indicator.

 Mild-moderate risk for relationship distress

% participants scoring ‘clinically distressed’ (<12) on the Brief Dyadic Adjustment Scale [23]

% participants scoring “high” (> 29) on the COVID-19 Family Stressor Scale [24]

< 50% of eligible participants.

 Participant retention

% participants who remain in study until end of post-intervention assessment

> 90% of participants.

 Participant adherence

% participants who complete 2/3 intervention sessions

> 90% of participants.

 Participant uptake

% participants reporting some use of conflict reappraisal outside of sessions

> 80% of participants.

 Acceptability

% of participants reporting at least “good” on 80% or more indicators on an Implementation Acceptability Scale assessing attitude, burden, perceived effectiveness, and ethicality [25]

> 80% of participants, (stratified by gender, immigrant status, and racialized groups).

 Primary outcome measure development

Objective assessment of we-ness [19] based on content analysis of writing samples. Will include an analysis of first-person plural pronouns (we, us, our, ours), reference to partners’ internal states (beliefs, desires, intentions), and positive affective language [26]

Inter-rater reliability (Cronbach’s alpha > .80).

Internal consistency (Cronbach’s alpha > .70).

Significant group differences between male and female participants based on t-tests (p < .05).

Significant correlations (p < .05) with indices of convergent validity (i.e., self-reported responsiveness, partner reported perceived partner responsiveness).

 Pre-post change in outcome measures

Couples’ relationship quality: Perceived Relationship Quality Components(PRQC) Inventory [27].

Intervention will improve outcomes from baseline to post-intervention surveys.

3-level multilevel models, similar to regression analysis but accounting for clustering within the data structure

Conflict-related negativity: two items following fact-based summary: “I was angry at my partner for his/her behavior during this conflict,” “My partner’s behavior during this conflict was highly upsetting to me” [14].

Perceived partner responsiveness/responsiveness directed towards partner: two eight-item scales will assess participants’ perceptions of their partners’ responsiveness/insensitivity and their own responsiveness/insensitivity towards their partner, respectively [28].

Parent-child relations, Parenting Practices Scale from the Ontario Child Health Study [29].

Parent Mental Health, K10 Psychological Distress Scale [30].

Child emotional and behavioral problems, Pediatric Symptom Checklist (baby, preschool, and standard versions) [31].