Jason / Laurell K. Hamilton.

Enhanced descriptions from Syndetics:

"Enjoying pain with your pleasure is something you either get, or you don't. If you get it, then you don't really need it explained, because you know how good it feels, and if you don't get it then no amount of talking is going to convince you it makes sense."

But sometimes you have to explain the unexplainable, especially if the love of your life needs to understand, or she'll leave you. Jason Schuyler is one of Anita Blake's best friends and favorite werewolves, with benefits. J.J. is his lady love, an old flame from childhood who dances at one of the top ballet companies in New York. She's accomplished, beautiful, and she's crazy about him, too. Neither of them wants to be monogamous, so what could go wrong?

J.J. is enthusiastically bisexual, with an emphasis on the female side of things. She plans to keep sleeping with women, because Jason can't meet that need, just like she can't meet Jason's need for rough sex and bondage. J.J. doesn't understand why Jason isn't content to go elsewhere for a need she can't fulfil, so Jason asks Anita to help him explain.

Anita is having her own relationship growing pains with her only female lover ever, Jade. Jason suggests that J.J. might be able to help Anita with her girl problem, while she helps him with his kinky explanations. With some encouragement from a few other lovers in Anita's life she reluctantly agrees, and J. J. makes plans to fly into town for an experience that none of them will ever forget.