Everything Justine says & does is obviously suspect.
But I think whampires have a very very different perspective on sex & love than the rest of us.
My whole issue with that scene from the end of Ghost Story is that bypassing the restrictions of "True Love" should be part of "Whampire 101" training that they all get after first kill but before they strike out on their own. Thomas should have already known all that.
Thomas did know it, he talks to Harry about it in the case of his little sister Inari in Blood Rights. That's the whole point of that scene when Justine brings her girl friend home to have sex with the full knowledge of Thomas,
so they could consummate their true love without burning. What's unclear, is why lesbian sex was chosen to break the true love protection by Justine and possibly Thomas as well. No, it shouldn't have made a difference, sex with another is sex with another, and would break the protection..
Thomas didn't want to be unfaithful to Justine. He probably knew the workaround but didn't bring it up because that might have hurt her or at least undermined her confidence.
And there is a chance that he didn't know it. Falling in love with a mortal is probably not a widely discussed topic in White Court society. (Hmmn, what happens if two White Court vampires fall in love?)
Yeah, he knew it about it, Thomas also wasn't thinking straight at the time of Ghost Story... However does feeding fall into the same category as having ordinary sexual contact with another to break the true love protection? We've had this debate here before, if Justine was raped, would her true love protection have been shattered? Is there a WOJ on this? How do you define it, rape is an act of violence, but it involves sexual contact.. What about the young women Thomas after the Skin Walker was done with him, had sex with and fed upon until they died? Maybe the true love protection was already blown long before that scene in Ghost Story?