I am in an interracial relationship… I am Rromani Gypsy, my wife is white. Your sociology professor sounds like s/he is farther behind you because you are not limiting your question to black and white while the statement from your professor is limiting it to black and white.
A problem is lack of acceptance from society in general which, luckily, is passing. That can have violent results.
Another problem can be lack of acceptance from the families. That can be a huge problem, probably the biggest in my opinion. I think that this one destroys many interracial relationships.
Then, yes, there can be cultural clashes between the two individuals involved. This can be mild, the two people being from similar enough cultures to not take much adaption, t severe, the two people being from vastly different cultures.
This takes understanding, a willingness to learn, and a willingness on both parties to bend and meet halfway.
The “black and white people do not understand each other” statement which, aside from being annoying in the assumption that black and white are the only ethnicities in interracial relationships, is not so. As I said, some people have divergent cultures they have to deal with but, if they care, then can and will understand each other.
Not being able to understand someone is simply lack of caring enough to learn. If you love someone, you and that person shall put forth the effort to learn.