A little lost

My name is Chris, My girl and I are having issues. She has had trust issues with me from the beginning. Shes scared of being hurt, like anyone else. We have had some bumps along the road like anyone else. Few my fault where i saw i wasn't doing anything wrong but she did. SO her trust weakened. We are still together but i see it falling apart. She says she still loves me but its not like it use to be. An ex fling came into her life last week. they are actually out hanging today, she asked if she could go. I said cool because she has never hurt or betrayed me. I trust her. Well i feel really uncomfortable about this, worrying she will grow something for him and ill be in the dust. I just want to build that passion back up, I know its possible, I know its there. Im just at a loss on what to do now. Her best friend said that shes still all about me, but i see the change and i know shes afraid to let me back in. What to do

dont lose your mind