How do I tell this girl I'm no longer interested in her?

We went out a couple of times and I realized she's not the person I thought she was. It kinda sucks because I did the pursuing and she seems more and more involved (she asked me to spend the night at her place) but I don't want to lead her on and be a f-boy.

What do I do

How do I tell this girl I'm no longer interested in her?
Post Opinion