Break up time?!?!

Zoey💞🌻
When can you decide whether it's time to break up with your SO or keep trying?? 
I keep having thoughts of breaking up with my bf because just everything about our relationship is going bad. The sex is bad, I literally have to beg and then when we actually end up doing it, it only lasts like 5 minutes. I'm bored with him, nothing is exciting anymore. I don't feel as attracted to him as I used to. & just little things that he does annoy me SO bad now. 
But at the same time I LOVE HIM SO MUCH, we've gone through so much together & I can't imagine my life without him now. He's like a best friend. The thought of us breaking up makes me cry and feel really bad but I'm starting to think its time. What do you guys think??? Sorry this post is so long I just need advice :/