Man, it's a porn game so of course it's going to give you opportunities (not force you) to go the other way around.
It would be a crappy game if it didn't.
But so far the game hasn't forced you to do anything at all.
You can refuse to see the girls' boobs, you can a refuse a date with Ashley, a date with Jenny, seeing Valerie naked, having fun with Jade, swimming with Rebecca, etc.
If you go on a date, you can refuse to say you are interested, to tell them you are attracted to them, etc.
You can refuse everything.
If you only like Ashley you can choose to be with her and even have an option to say "she is the one."
If you like Jenny, you can avoid doing anything with the others, while waiting for her to make up her damned mind.
The same applies to Valerie. I have a route where she is my LI.
Will the game allow you to cheat on them after all this? Quite probably, but that's how it is in real life too; you don't get locked out of sexy content after getting yourself a girlfriend, nor even after getting married
.
It will be up to you to decide what to do.