Tell or not to tell that is the question?

No.

Well, this one girl that I'm interested in has a boyfriend but she never told me even tho I told her how I felt about her and such and she still talks to me and she always insists that we hangout and stuff. So I'm not really sure what to think, she even said she loved me although I'm assuming as a friend but all good relationships start as friendship. Personally : I wouldn't tell them unless they asked cause it's really none of their business even if they do like me.

Be truthful to them that's all I gotta say...

Just remember to always be truthful and upfront with the person you are actually with. If you decide to try other things out don't try and hide it because its no crime to test the waters but cheating and lying will only leave people hurt.

Just say that you are just testing where the waters will take you.