Is it possible that YM isn't working my pword is correct and also the id?

before i use my bf's YM and he uses mine. he wants that way whenever we chat, he says it better so that we will not think that one of us is chatting with other chatters and flirting at the same time. so we did it that way. after a month we fought coz of something. so what we did is we change our pwords in all accounts. but then, we maked up and start smoothly again but there's something change he use his YM and i use mine. so i asked him again, can we exchange our YM like before? and then he said okay, i gave him my new pasword and he gave his new pasword. but, i tried logging in for a hundred times and now its already 2 days still the pword that i am trying to log in, the pword that he gave me is INVALID! for a hundred times. i asked him did u change? is that ur real pword? and hea said so many times YES! i dont have other pword and i sai but i can't log in, but how come u can log in? i can't enter ur YM but u? u can chat with me and u can log in to ur YM why me no? he said, i dont know...i didn't change it. are we going to fight again u said we will be better but now ur doubting that im lying on that password. that's what he said. i tried other pc thinking that my pc is the problem but until this time i can't log in...help me? is he telling me the truth? or is it sometimes yahoo problem? but how come HE CAN LOG IN EXCEPT ME?! please im confused if i have to trust my boyfriend not hiding anything on his email and messanger please help...somebody save me please....