Yeah, I think there is the exotic factor might be going on with some of those foreign women you are meeting. Just know they are human too, don't exotisize them too much, they might be all over you upon first meeting, but the true appreciation will come out in how well they treat you long term, if you go or have gone long term that is.
I also think it might come down to the cultural histories of the US and Europe. As we all know, the US has a long and deep ugly history of slavery. Although we are in the 21st century, interracial relationships are still quite taboo in many parts, so some American women might be reflecting this and you might be feeling this in their treatment of you, don't know.
Again though, don't write us all off altogether, we are varied as well, perhaps you have just not found a good US woman yet. Also, before placing any blame at another's feet or noticing their shortcomings, check yourself as well? is there anything you could be doing better to perhaps get results or relationships that feel right?
I have also thought that in many ways, Europe is a lot more progressive in general, especially when it comes to the environment and things like that, so it could follow into other areas as well, like culture and dating. In addition, some of the European nations are older than the US so they have had more time to develop melting pots and culture mixing, and progressive attitudes and ideas. Not that the US all a bad place, it has its unique qualities as well, just different vibes and cultures.