One of them is Harlan Coben's "Miss You." Close to the end he has this speech about how terrific gay love is. It wasn't relevant to the plot. Others have also commented on this.Maybe he is gay and got carried away with his one fantasies. Somebody wondered if there is a requirement to include a gay person in mysteries.
I have noticed that too. Extramarital sex has been de rigueur for a long time, but the adorable gay people are a new development. One of the reasons I like the C. J. Box books is that the hero is a faithfully married man. Swoon.
When the first novel appears in which the gay person is the murderer, then we will know they have arrived.