im looking for a yaoi.. well im not sure if its an yaoi XDD

could even be a shoujo... my memory is so fuzzy... but i want to believe with all my might it was a shounen ai or yaoi... ><

and another problem is.. i only remember... the main protagnist being threathened by a really smart guy (darkhaired)

because he couldnt believe the main protoganist?

uhmmm

wishing to kill himself with the protogonist but getting saved :S

its not Komatta Toki ni wa Hoshi ni Kike!

serly not enough info for anything.....

Your description reminds me of the manga Power!! it isn't a yaoi but you did say it could even be a shoujo.
There is a black haired dude in it who wants to kill himself and drags the main character along with him. (he also doesn't believe the main character when she insists she is his friend)
Failing all else - do read this one if you haven't already ~ it rocks

i believe it is this one XD

no wonder i thought it could be a shounen ai or a yaoi its a gender bender XD

and yes i did finish this one completly XD

and im gonna read it again right now XD