Why do I seem to mess up good relationships sometimes?

When I was 21 or 22 back in 2009 I dated someone and loved them deeply. Problem was that I had some problems with them and instead of dealing with them and talking things out I ran away. I took a break from them and then called them and told them a lie that I don’t love them anymore and the relationship is over. I closed my heart up and refused to let myself have any real feelings for them. I’ve regretted that day my whole life. One day they friend requested me on Facebook and we’ve been talking and I admitted to them what I did and how bad I’ve felt all these years about it. And I litterally cried. It felt good to get some closure from it. Fast forward to now; my current boyfriend we’ve had some issues off and on but instead of talking to him about it I’ve been doing the same thing just running away. We live together and I just camp my butt in front of the tv and ignore him. I almost broke up with him even though I still love him without even talking to him about my problems or how I feel and working through things together. I was about to make the same mistake I made years ago but I stopped myself and now we’re working things out! I need to change this behavior cause it’s toxic. Once I start to love someone I’m afraid of getting hurt again so I close myself off from loving them. I want to stop behaving this way. Any other suggestions.