Without any strict rules or expectations on your part, your new boyfriend is going to see how the night is going before considering a move to have sex with you.
Your consent to sleeping over without rules leaves him open to the idea that as long as the night goes well, you show a desire to have sex with him.
The maturity of your relationship is a factor too.
A past of messing around with each other, kissing and touching, but never finishing with sex, sends a message that now you are sleeping over at his house, you are going to finish it off with sex.
There are some guys who don’t like kissing to an extent, and it doesn’t have anything to do with having a problem with the girl in question.
The physical act itself isn’t the underlying cause for their dislike.
Rather, so much of it has to do with how comfortable they are with you emotionally and with themselves.
There are lots of guys who aren’t quite right with themselves emotionally.
Believing that society deems they have a macho persona to fit in, they adopt that persona, fearful of being judged harshly by exhibiting characteristics that are more in line with their emotions.
Your consent to sleeping over without rules leaves him open to the idea that as long as the night goes well, you show a desire to have sex with him.
To this effect, people like to feel like they are a part of the norm.
This isn’t a situation where you grin and bare it. 
The physical act itself isn’t the underlying cause for their dislike. 
Although he isn’t obligated to go, applying subtlety to sell him on the