Do you really think that Wade would immediately fuck his friend's girlfriend as soon as she offered, literally next door to his friend's room, despite being in relationship himself?I might be misremembering some stuff (I was a little high while I was playing it), but back at the house, isn't it implied that Lena and Wade do something while Ian goes to bed? She straight up tells him to go to bed, even if I try to make him stick around to keep an eye on them.
Lena tells Ian after she returns that she has talked with Wade about possible threesome, and that Wade said he would be up for it if he was single. There's little reason to think she'd be lying -- if Ian is on cuck path then Lena would have no reason to keep from him sexual stuff she's doing with other guys.