Should I just give up?

My partner and I have been together for 4 years. No relationship is perfect, but it was pretty great. All of the sudden we had an argument, he says Im not the woman he fell in love with, accuses me of being a lesbian, when he knows Im bi and I am further in the spectrum towards hetero. But he says that one either is or isn't, I guess to him bi doesnt exist. Anyway, we are trying to work it out. Its only been a week, but I feel like Im living in a nightmare. I really do love him, but now he isnt the same... he seems careless, like he's just waiting for me to leave. this sucks.