toptobottom, RVDT,
While personal relationships and personal issues may be relevant, they are unlikely to be considered outside of professional CRM issues aboard the aircraft. If there were known issues prior to the flight, management will be heavily censured and criticised for not doing anything about it. Close or familial relationships are generally forbidden between officers serving together, although it is not unknown for husband and wife to serve at the same station and/or work together in the same vehicle. The problem is that allegations of collusion will be levelled if an account of events by such officers is disputed.
If such matters are considered, it is likely that that part of the FAI will be heard behind closed doors and the conclusions omitted from the final report unless they point directly to being a primary cause of this incident.