CloudEe's feed

I think this will be vague bcs I read this last year and I don't remember much, I just suddenly. It about a girl who's 14 when she was isekai and then there's this old knight If I remember he is 60 or something old then the fl actually became his fiance bcs of the royals (I think) then they started living together and fall for each other. The last thing I remember after they got married then they have sex then the old guy becomes his younger self again. Ohhh I'm so sorry that's all I remember（/TДT)/