White Collar, ftm!Neal (slash with Peter welcome). Peter knows all the intimate details of Neal's life, and he's used each of them against him, except for this.

Diana gets annoyed at Neal for flirting with her, he admits that he only flirts so much because it doesn't mean anything. He confesses that he's never come out to anyone but Kate, and he doesn't want to lie to Peter, but he's also scared that coming out will cause him to lose the most important person in his life. Diana helps and encourages him.