If a young girl has her heart set on settling down with somebody and having kids with them there isn't an awful lot her family can do to stop her, apart from trying to be there when she needs them.
If they try to get too heavy she will simply cut them out, don't you realise that? This kid had her heart set on being with this character and having a family with him, why do you think that was? Do you think it might have been because he told her how much he loved her, and how much he wanted to be with her, and how much he wanted lots of kids? I sure as hell do.

Being "not quite right" as you put it just makes her more vulnerable to gobsh***s like this. Do you still think he should be blameless?