Why do some blackwomen get mad when a blackguy dates a white/asian/hispanic girl when she turned him down?

I have a AA male friend who i work with! He is one of the smartest guys i ever worked with in the engineering computer field. Anyways, we usually go out for drink at fridays or a bar downtown. There are tons of blackwomen who go together as groups or couples to fridays.. It seems like every time he goes over to just to introduce himself, they give him a look like he just came from outer-space and rejects him. I noticed that most i would say 90% of blackgirls rejects him He is 6'0 and one black girl even said he was not tall enough for her while she looked no taller then 5'5 WTF? Anyways he now has a girlfriend (who is hispanic/white) and is very pretty.. Well last week we went to the same bar for dinner and he just gets the looks of death from black women there.. He said that black women will reject black men and they turn around and get all pissy talking about theres not good black men to date when they are right under their noses? And another reason i ask is because on youtube there are many videos of black women complaining that they cant find a good blackman, well isnt it because you reject them for thugs when your young and when you get older you expect the same guy to come running back to you when your done playing with the thugs or have babies with them.. Is that true?