Step mom and dad fight?

my dad and stepmom, trang always fight. i dont know what to do. my stepmom drives away in her car sometimes and doesnt come back for a while. and my dad thinks shes with her EX still, thts why they fight. he doesnt trust her. but i dont want them to break up. i have been attatched to my stepmom like shes my own mom. and i dont know who's right