it goes back to a little more than just what they've become.
and white girls have issues, too. trust.
it could be like ya setshego said...he might have just wanted an excuse to persue white women, so he keeps going after the same type of blk woman.
or...there are some addtl considerations...
do they want a thug 'cause they were *raised* by one (an issue rarely discussed) or because that's what's "cool"?
what's the general culture of the area where he lives?
how old is he? how old are these women? has he considered an older woman?
where is he meeting them? might be better to stay out of the club (even "grown folks'" spots) and/or steer away from random meetings and join w/ a group that shares his interests...something like that.
it's been my experience that if you continually encounter the same patterns--especially in relationships--there's something you need to learn. or something you're not getting/haven't healed within.