VERY clingy boyfriend? Please help..10points?

I'm a guy and I used to be clingy. I had a girlfriend who told her best friend that I was too clingy. But she never told me, I found out a week after she broke up with me. The relationship didnt last long. All she had to do was tell me and I would understand and back off a bit. In my opinion, if you're boyfriend understands you then he will understand where you're coming from if you just tell him to back off a little bit. But don't be harsh. Guys sometimes understand better if you're not harsh.