Has a relationship changed me?

It may be you maturing, but I dont really think so. I'm still as outgoing as i was when i was 15. So yeah, it could be your former flame took some of your confidence. Get it back! Don't let her do that. Now, as for if your relationship changed you. Yes, it did. All relationships change you a little. Whether it be romantic, or just a friend, they all help mold you.