I think fear plays a large part in any conflict. Fear of loss maybe? Of control? Of rejection? Of change?
Some members of an ethnic group may want to "blend in" and assimilate. That could make daily life easier for them if they fear hostily or lack of acceptance. But that also requires a degree of courage, to make that decision. For a person who is very traditional in their own culture, they may feel that they are giving up a part of themselves, what we would call "selling out".
I think this explains why immigrants sometimes lose their native language. They may want to blend in, so they will not be singled out. As a person who majored in Psych, we are told that we like people who are like us, that agree with us, and so forth. No one wants to be isolated.
Intergrating requires keeping a delicate balance. Keeping my culture, keeping my language, but adapting enough from the environment to build bridges to the new culture. That's a tough job for anyone. And if you throw in other stressors, like housing, language barrier, trying to do your job....well it get's that much harder.
I have a lot of respect for anyone who moves to another country to settle.