All of the main characters can be hooked up with in the game, although one character needs to be romanced first. You can definitely hook up with Will, though that isn't in the game yet. I think there'd be a riot if I wouldn't let players hook up with him, haha.
However, all the sex scenes in the game will show the player character Connor hooking up with other guys since he's the viewpoint character. On Patreon, I do galleries of the non-Connor main characters hooking up with each other, which aren't scenes you'll see in game, especially since most are fantasy scenarios that wouldn't necessarily make sense story-wise.
So for instance, last month I did a hookup gallery of Matt and Riley, but that won't be something you will see while playing the game itself.