I just checked the banter to see how it goes and I don't think it's abusive either. Bull just comes off as a bit of a douche here and there but that's not anywhere near abusive territory. Perhaps if the dialogue wasn't so...aggressive? Bold? (Are those the words I'm looking for?) on Bull's end, people might have seen things differently? (That's a lot of question marks >_> )
The only times Bull comes off as a bit of a jerk when he feels the need to speak about their escapades in public, making Dorian seem a bit uncomfortable.
And I ensure you, that's not what Bull wants to do.
When you romance Bull, he makes it 100% clear what the rules are and that he will NEVER intentionally hurt you, and at any point, when you are uncomfortable, whether in sex or in the relationship, you can talk to him and tell him to stop. His role in the relationship is to give you what you need, and he does that.
With Dorian, his main objective seems to be to make Dorian comfortable with himself, as a gay man. He speaks about their relationship very casually, to ensure Dorian that it's nothing shameful, nothing to feel bad about, and that they have the right to love each other, in public and in private, without feeling like it's something to hide. He wants to give him confidence. Whether Dorian understands this at first, he might not, but in Trespasser, his relationship with Bull has definitely matured and there's definitely mutual love and respect between them.
If you saved the Chargers and Bull doesn't betray you, is in a relationship with Dorian and you got Dorian in your party, they will openly exchange '' kadan '' and '' amatus '' with each other after the battle where Bull either betrays you or doesn't.
I think both of them come to really appreciate each other in the end, even though their start is rocky. I think Bull might've begun the relationship because he thought that it could be beneficial to Dorian who's company he came to enjoy and appreciate, and Dorian wasn't sure about what he wanted, but in the end, there is love there, a love that is healthy.