How to overcome negative relationship thoughts?

I’m not sure why but lately I keep getting the thought that me and my bf shouldn’t be together, even though he’s so incredibly amazing to me❤️ we’ve been recovering from a rough patch and I think all the negativity and fighting that was once there is still with me. I only get this thought that we’re not meant to be when we have a disagreeance. How can I over come my own personal problems of interpreting things worse then they are/to not get frustrated and resort to those thoughts. Any tips would be amazing including any communication skills. Thanks girls:)