yes, it's difficult to trust but makes u feel relaxed when u do. it's not a matter of boy/girl friend stuff. a friend who cares in time of need and trouble, a friend whom u can confide in is worth the trust. and with dat kind of person when u r with him/her u can go to sleep with ur eyes firmly closed knowing u r save with him/her.
why would u hv boy/girlfriend u don't trust? if u don't him/her then there is no relationship. u two r merely hving sex relationship which is a short term thing.