<human>: Can you condense the text into three sentences or less?

Title says it, I am a 25 year old male. I just ruined a relationship with a great girl. I over thought everything in the relationship. I kept secrets because I feel that if it's not worth telling she doesn't need to know. I am a very pessimistic person. I see the negative in everything. 

The thing is that I really do like her, but I keep things from her and it pisses her off. But it's my nature to not tell anyone certain aspects of what I do during my day. I feel that it's not important at all. 

I've told some lies to keep myself from getting hurt too. She told me that I need to be happy with myself before we can continue. I don't know how to be happy with myself though.

There's more about me but I don't want to give you guys my life story.
<bot>: I over think everything, I keep secrets and I tell some lies to keep myself from getting hurt. And I am not happy with myself. Help would be great.