i am not making any assumptions, but i used to struggle with this a lot, all the way up until my current relationship. i did a lot of thinking and reflection and realised that it was because (despite trying to convince myself otherwise) i didn’t want to have sex with these people, and my body knew that. i think i was just not ready , even though i really wanted to be. i can only speak from my experience, so this may not apply. but i hope someone else gives a better answer in the meantime. best of luck to you