First off, even though you put up with it outwardly, your family relationships leave you both hurt and pissed. Obviously I'm refering to some family members over others. So it's not exclusively a dating thing.
Secondly, with regards to a partner, being hurt or pissed roughly corresponds to "believing they are wrong" vs "believing they are right". I'm commenting in general here.
Thirdly, you're not a shitty g/f. You just haven't found the right girl for you... err... guy. Well, MF is probably the long-term solution but FF could be fun.
Besides, I'm the asshole, remember? Have you ever met anyone who has known me in real life who would argue this? What would Bronwyn say if you asked her directly, eh? So don't be self-blaming.
...You bastard.