Hi there! Decisions in CH are generally not going to lock you out of full paths. You might miss a scene or two as an immediate consequence of a choice you made, but you'll have another chance to get back onto a girl's path later on, once it becomes relevant again, as long as it makes sense within the confines of the game.
There might be rare exceptions in the future, but so far I don't have any concrete plans for those kind of choices.
I'm also really glad to hear that you enjoy CH. :)