As in title My [M27] Fiancee [31F] favourite kind of sex recently (few months now) is falling asleep while i fuck her and watch porn with headphones on. She always encourages it and gets more turned on while i do it (and even seems disappointed if i tell her i dont want to watch porn)

I tried bringing it up subtly but she always gets shy. I tried to talk about the kink or suggest maybe a threesome (she's bi) but again, she gets shy and changes the subject saying that she doesnt know or maybe. I dont want to push her or overstep especially if it turns out it is potencially her new kink. I know its all about communication and i dont want to seem like i want to fuck around or cheat on her, i just want her to feel free to express herself and explore what she finds hot but i cant find a way for her to really open up and i dont know what to do about it or even if i should.

Im not her first but she's mine, i hadnt been with anyone besides her and we have been together for 7 years now if it matters.

Appreciate all help and advice.