I'm not going to give you a 2x4 - maybe a 1x3? That's great that she's confiding in you. Make sure you aren't simply supporting her justifications. Don't walk on eggshells. She isn't, but it sounds like you are. Is getting a place with a live-in friend really providing stability? If they aren't together and she starts dating again, that'd mean D has 3 men in her life. Doesn't sound all that stable to me.
I don't want to insert negativity into something positive, but I don't think you should be a doormat or walk on eggshells. Think through what's going on and what the best course of action is and be true to yourself.
Of course, I don't really know what's going on in your sitch and this may not be applicable. But I hope it's useful. lodo
