Can I reveal my feelings to a coworker even though he has a girlfriend?
This sounds like a joke. Why do you want to share your feelings with him if he is already in a relationship?
Because I feel like he is perfect for me and we hit it off really well. I feel like we work together really well and we could maybe move in together in the future.
Besides it being a bad idea to start a relationship with someone you work with, it is inappropriate to make advance toward someone who is already in a relationship. If you and this person are really perfect for each other, it will work out in time. You shouldn't try to break up a relationship that people are happy in just because you want one of the people in it for yourself.
Actually, I'm just fine with both ways.
You will be getting into some sort of trouble if you do this. I know it, been there done that. Try to wean yourself off of this married fellow for your own sake and no one else's.