Ben had a crush on Poe but never approached him. Time skip to the movie - he is reading Poe's mind and finds out that Poe was in love with Ben and still grieves for him (whether he knows that Kylo is Ben or thinks he was killed is up to you).

Can lead to Kylo turning to the light or cutting all ties with the past and fully embracing the dark side, but no non-con/dub-con, please.