While I can appreciate you wanting to help this drama isn’t yours to dive into. As much as you care for this woman, it is clear that the couple has issues they need to cope with on their own. You getting directly involved in trying to fix this isn’t what you’ll want to do, as it prevents them from doing what needs to be done to fix or end the relationship.
If is hard to know exactly what your relationship with her actually is when you say “loved one”, but in your capacity the best thing you could do is help her get some therapy. You may want to try the woman’s center near where you live or check the “find help” tab at the top of this page.
The complex, difficult, and ongoing nature of these issues requires more support than a loved one could provide. Helping her get some professional help or a support group near where she lives would be best. Perhaps you could offer to go with her to her first appointment.
Wishing you patience and peace,
Proof Positive Blog @ PsychCentral