I hate that my partner is a sanctimommy
What is bad about being a sanctimommy?
It's the absence of discourse.  They leave no room for discussion
Have you tried talking to them about how you feel? If you feel you cannot deal with this it might be better to break up before you get more serious.
I'd have to break up with him.
You have the right to be secure and happy in your romantic relationships. I think you should try to talk about it with them before you break up to see if you can work through the problem.