How 2 Know He Is No More Interested.

if he does not call you
like he used tooo
when he starts this disrespecting you
he does not buy a gift for any holiday or birthday or even valentines day
when sleep beside him and he does not touch you every time you see him
you guys argue constantly every day
he is giving you  clues that he wants out of the relationships

when he does not talk to you for days. even though he see you.
when he gives, but you don't receive.

all that the other 2 posters have said.
perhaps he needs lithium