It's not like that for Dan and Gary, or at least they are not like that for the reader. Dan and Gary are cops, partners, not yet lovers, but they are not invincible, and the reader have plenty of chances to see their faults. Gary is running away from a past who saw him a victim, and the drama he lived it's conditioning his present. He is unable to build a serious relationship with a woman, and probably he desires another man since in his mind it's something of unreachable, and so he is not risking to have and loose it. But one thing is the mind and another thing is the heart, and in his heart Gary knows that his only salvation lies in Dan. And so he doesn't let it go any occasion in which he can tease Dan.
I forgot to mention that this is a continuing series of four part, and this one is only a novella, so there are a lot of things that are a bit suspended. One of them is Dan's fully development. We saw his desire for Gary, probably we understand that he is in the closet, since nor at work or in his private life he is living like a gay man out. So his desire for Gary is not something that makes him doubt himself, but more a problem due to their differences: Gary is apparently straight, he is too young for him (a rookie where he was a full grown cop), Dan is the by-the-book cop while Gary seems to be out of 21 Jump Street (and this made me smile, since that was a television fiction I saw when I was very young, and so maybe the author has more or less my same age... even if I was really more a Renegades fan).
And now sorry, maybe this could be considered a SPOILER, so stop here if you don't want it, but since the Chasers of Torquere Press are continuing series, probably it will be not surprise if I say that, truth be told nor of Dan or of Gary we see the fully development, if not for the blossom of their relationship: Gary will admit that he has some unresolved questions in his past, Dan will admit that he is gay and that he is in love with his partner... from that point on, we have to wait for the next chapter. And I will for sure read it, since these are two characters that made me feel for them.