Help Please

Brian and i have been together for 3 years on an off well yesterday he said we need to break up.. he says our relationship is stressing him out and he loses sleep at night and can't function during tha day he say he needs time to think and all he wants to do is be happy.. i don't know what to do i love him so much!! I do blame myself though because i have been very stressed out and im not to nice to him! If anyone can help i would be very thankful!