GUYS how do u feel wen a girl tells u that...? ?

I was just woundering how dose it make u feel wen a girl tells u "Ur a nice guy but..." lik wen shes breaking up with u or rejecting u? Do u believe her? Because my sister has been saying it to alot of guys lately nd i jus kind of feel bad for them for sum reason. I just want to kno how u feel wen they tell u that??