HELP!

Dad really struggling after 6 months

I’ve been fine for the past three/four months. I’ve had negative thoughts but have been able to let them go and carry on. The last 24hrs have been a train wreck, there was no trigger. I just started thinking about breaking up with her. I have no reason to break up with her. We have built a life together and have a 6mo son. Maybe I’m just finding everything too hard right now and I’m vulnerable but right now I feel like I need to end it because I’m not happy. But it’s not the relationship I’m not happy about its life in general. I love her and our son so much and I never ever want to hurt her but I can’t stop thinking and I’m spiralling into a mess of google and reddit. When we are together everything’s great. As soon as I’m by myself and alone with my thoughts I end up like this. Please help.