How did you know it was time to move on?

Me and my fiancé have been together four years and it has been good for the most part. Obviously its been hard at times but its been good more then it has been bad but for the last couple of months things have been horrible between us. Its like we constantly fight every single day with maybe one or two good days every now and then. I feel like he just is so checked out of the relationship and it makes me so upset we have a son together and i have two more kiddos from a previous relationship that hes been apart of their life from the beginning and it just breaks my heart of tearing our family apart. I know he loves me but it just doesnt feel like hes in love with me anymore and it hurts i have made this man my every thing and i dont know how to just let go but i need more. Ive tried to communicate and talk to him about it but he just shuts down or tells me it's all in my head. We use to be obsessed with each other and now i feel like i have to beg him for his attention. I feel like he's comfortable with me and that's why he stays. Hes so checked out of the relationship and he doesnt see it. I love this man with absolutely everything in me but i need more. I stay up late thinking about what went wrong. Would you hold on and hope it got better or would you just end it now?! Im so confused i just can't imagine life without him but i dont wanna be with someone who doesnt wanna be with me. He says he does wanna be with me but his words and actions just dont match. Is this just a rough patch in life or is it over. Im so confused.