Let me ease your pain bro! LOL
Statistically most people of every ethnicity date and marry their own people at the highest rates at least two thirds so based on that you guys have absolutely nothing to fear. Now that doesn't mean that they won't fantasize or experiment if they get the chance but for the most part you are the number one preference of your own women.
Studies have shown that most women consider black men more masculine and more attractive than other men and that is probably because of the melanin which gives us our color and also protects us against the sun and aging as fast as others. Many women in those European countries admit to wanting a biracial or exotic baby and trust me I would love to be a cereal baby daddy in Europe. LOL. This is the academic and genetic side of it.
The reality is that black men are different and exotic to these women and they like the way we dance and sing and how we fuck in porn movies. There is also the stereotype that all of us have big cocks. Now even though it's not entirely accurate many women have hit the big black cock lottery and had life changing experiences then went and told all their friends and now their friends are fantasizing and want that experience too.
Lastly as far as taking a woman away from another man, no man who has respect for himself would take anything that belongs to another man whether it be love or property. Karma has a funny way of repaying those who take what doesn't belong to them. Also as a bull in the swing lifestyle guys like me are interested in taking women from anyone we just want to borrow and fuck the ******* out of them! The only thing that's going to be missing is how tight your woman was when y'all got together!