Very emmotional right now

I don't undertand what is WRONG with me. I can't seem to get the discipline back that I used to have within myself. I was going to the gym working out and trying to eat healthy. Then I fell off track again. It's been 3 weeks since I have been back at the gym. It's effecting my relationship with FH bc it seems real important to him that I lose weight. Not just for the wedding but as a healthy way of life. He is mad b/c he does not think that I WANT to lose the weight. I DO it's just that it pisses me off when he says his comments. I start thinking.. ok if he really loved me for me why is he SO concerned with me losing weight. I am not overweight.. I don't think.. I am 142 and I'm 5'4' but I was 125 when I first met him. I just feel all these emmotions right now.. mad, sad,, I am mad b/c he is getting so bothered by me not being on a strict schedule to lose the weight and honestly it just makes me feel WORSE. UGH.... I just want to scream! I am not even talking to him right now. He went into the living room and now we are both pissed at eachother..... I am writing this to reach out.. I feel sooo depressed right now.