We've been friends for about 10 years and after about 6 years of friendship we started sleeping together while we both had traveling jobs. Eventually we did decide to start dating and see where it would go. It was a strain on both of us as we had difficulty communicating and finding time with each other. We broke up for about 2 months. 

During that break she was on tinder and starting sleeping with a guy. Things happen, she was single and I completely understand. We ended up starting to be friendly again and fell right back into dating. She had only been seeing this guy for a couple of weeks and only knew him from Tinder. 

After we got back together I noticed that she kept chatting with him. What really got to me was on New Years Eve he texted her  and she was chatting with him briefly. I had a very frank discussion with her that it seemed strange to me and it felt like she wasn't cheating but basically keeping him in reserve if it didn't work out between us. She said she would stop talking to him. After that, we still both had our traveling jobs and would only see each other monthly and really didn't learn anything from the previous times so eventually we wound up breaking up again. It's been about 6 months and we're doing our best to renew our friendship as much as possible but she admitted he was the first person she slept with after we broke up. 

In our time, I was never insecure about being on the road, I feel very secure we wouldn't cheat on each other but that was the one thing I was insecure about and it ended up manifesting itself to be true. She says it's not wrong, which is true, but I still feel disrespected. 

Thoughts? 