My girlfriend and I are have big problems in our relationship due to lack of or no trust at all. My girlfriend is feeling very insecure and emotionally unsafe with me, to the point of losing all trust in me because of things that I've said and done.
I told her about things that I had done in my past...for example...

When I was younger, I had kissed my friend's girlfriend, nothing eventuated from that kiss, it was just one of those things, but this left my girlfriend with doubts of whether this could or would happen again or if I'm capable of being faithful within our relationship.
I told her how I used to be the only male that lived in a flat with all these other women. Nothing happened between any of the girls and I, but my girlfriend has doubts because I was capable of kissing someone else's girlfriend.
I told her about sleeping with two sisters, on separate occassions unbeknown to me at the time, and because my girlfriend has sisters, she is now doubtful in this area also.
I told her how I had had a sexual relationship only, that had no emotional bond or ties. This went on for a time with another woman and this has left my girlfriend doubting my ability to commit emotionally to her and our relationship.