You can mostly avoid having sex with guys if you'd like, though you may need to save scum a bit. Only one of the four romantic paths is with a guy. You can be free use for any of the romantic paths fairly easily, and then you'll be used by the four plus a couple others occasionally. If you go the free use path, you'll pretty much be locked into being a sub, yes. Everyone else will... well, use you as they want. To varying degrees. That's one of the reasons I said it's probably the one you're least interested in. It's also frustratingly dialogue heavy when it wants to be.
You'll probably like Lust Odyssey a lot more. You can have whatever junk you want and there's often both a 'dom' and 'sub' path for each character. It's one of the few games where I'm equally interested in both paths - usually one feels a lot more fleshed out than the other.
I also reread your post and saw you liked Breeders of Nephilim. While it's a completely different game (another text rpg), if you haven't played one of Fenoxo's games I suggest you should. It's got free roam, nearly everyone you meet will be eager for sex, it's frequently updated, and you have quite a lot of freedom over your character's body. It also allows you to dom nearly everyone you meet, just like Lust Odyssey. You've probably heard of them already though.
