I was referring to Anne though, the daughter.
To Warren it looked like some bastard came up with this huge intimidating army, marched to the capital and took the throne. Even if the queen gave it up willingly, Gregar still brought the host of mercenaries, so that kind of says he would have taken the throne by force. You could argue that the queen was forced to give up the throne, as why else would she refuse when Gregar has the backing of the mercenaries; there's no way she'd have argued with him.
Back on track though. So Warren still kind of sees it like Gregar waltzed right in and effectively 'stole' the throne (in Warren's eyes, mind you). This forced the queen to step down and marry her daughter off to Gregar. Yes, the queen offered the idea of marriage, but she would not have done so if Gregar didn't want the throne.
Warren might look at it like Anne was forced into her marriage; he'd prefer to have her marry the person she wants to marry, rather than marry some bastard who took the throne from her mother. I think he'd harbor a little resentment to Gregar, as he wanted to serve the royal family - not a Bastard King. But since he wants to faithfully serve Anne, he'll do the same for her children, and anyone she cares about.
But that's Warren's twisted view on things, not necessarily mine.