At a Complete Lost... Should I give up?

So I have been seeing this guy, I guess you could say off and on since high school. We moved in together this past year as well... and things were as always up and down. Recently around New Year’s we were talking about marriage and possibly having kids in the near future but recently we have broke it off... and I am not sure how to take it... like it was kind of mutual in a sense that we’re not good together... we don’t make one another happy... but the confusing part is when we always break up things are so much better. We get along, communicate, we’re supportive, we do more together, and have amazing sex... but as soon as we think things are good enough to try again as a couple, within a few weeks we fall apart again... it’s like we lose sight of things when we throw a label on our relationship and I m not sure why...

We fall apart when we are together, but amazing when we are not... I don’t know how to feel about it because we both love one another very much but we both see this problem and I just... I don’t know. The decision to break up feels so wrong but at the same time it is almost the right thing to do... but I don’t know... now I am in a position where I am not sure where to go from here. I don’t want to cut him out of my life because we are amazing best friends. It sounds so stupid... it feels stupid... but I just... I need advice... has anyone been in this position? What did you do about it? Did you end up with a happy ever after? Or did you walk away and never looked back... I don’t want to lose what we had/have but at the same time is that for the best? Could it ever work?

Signed,

Losing her mind... and kind of heartbroken...