that is a perfectly rational notion, on your part.Yea well that goes back to the problem..the daughter will not break up with him. I'd be fine if only she was here but she makes them a package deal and that is where are disagreement lies, girlfriend wants daughter here at all costs with him so be it, I don't, I feel like if he's coming too then I don't want them.
Personally, and this is just me, I would walk. Life's too short to kill yourself for people who not only don't want to be fixed - but refuse to admit they are broken. In the end you will keel over dead and they will go on with their merry dip-shittery.