will polish peolpe normally only date and marry polish?
Not only, but some feel closer to others of the same kind, it's easier for them to communicate in the same language, they grew up in the same country and they just feel closer, understand each other better and more relaxed with them.
But that's not always the case either. Some like to have a challenge of the unknown, the foreign, meet other people fom different countries and have a life filled with excitement.
It all depends on one's personality.