Most Helpful Girl
Follow that instinct and do not get involved until divorce papers are final and she or he has moved out of that house. If you jump the gun, assuming he is even into you, you are setting yourself up for some soap opera style drama that I can only guess, you don't need in your life.
My friends parents had been actively fighting and threatening divorce and leading separate lives in the same house since she was 13. She is now a senior in college, hasn't lived at home since she was 18, and just last year they finally finished the divorce and moved on. Relationships are complicated as are the people in them. They may hate each other, but either financially can't figure out how to separate or they could have a friendship or an understanding, but its none of your business.
If the guy has verbalized or shown you that he really is into you, it may be worth the wait, but if he has shown no reciprocal interest, you may be waiting around for a long time and for nothing. Good luck.