At one time, mixed couples might have been more tolerated in Europe.
Mix of what? White girl and black guy? No one would bat an eyelid. Well-to-do Egyptian Christian with a white girl? Again, nothing. A Muslim man of Pakistani origin with white girl, however, would be controversial, and the objections to such a mixed relationship will often be far stronger on the Pakistani side. Actually, objection to mixed-race relationships is something often cited by islamophobic or anti-immigration groups as proof of the reluctance of Muslim minorities to integrate and their disdain for the existing population.
Prejudice depends on which minority you're talking about. Right now, Muslims are the untouchables, and I don't think you can say American attitudes to Islam are more positive than they are in Europe. The kind of stuff said regularly by American politicians on TV, apparently considered acceptable discourse, would cost you your job in most European countries.
Talk to the black guys I knew in German, France, Austria, and Belgium.
Talk to nearly all the women I spoke with about this from those countries and more about dating a black guy.
There is a "fetish" of sorts for it, especially among the more elder single white European women. They frequent clubs usually for people more than a few decades their younger and buy black men their drinks and what not before retiring with home with them.
That is about as close I ever saw to any of the black Europeans I knew getting accepted by the women where we went.
Again, in the more hyper-ultra liberal snotty art crowd this was little different. Also I didn't see much of a taboo around in the gay bars and clubs I was in.