I don't understand how people are letting the fact that the guy is African cloud their judgment.
Let's get something straight there are plenty of men around the world who have dated females for a long time and won't wife them.
There are plenty of guys who will not introduce you to their parents
there are plenty of guys who is not ready to get married at such a young age
There are AA mothers who do not want their sons to marry darkskin/lightskin females, chicken heads, non college educated, etc
This to say culture is really not that different.
However no Nigerian or african guy will be married at such a young age. His family is more interested in him making a name for himself then meeting some girl. He knows that he does not need to get married until his schooling and job situation is on point. The ones that are about something will definite make it their priority. Marriage will come after 25yrs of age, and they are not sweating it.
So all this to say that dating you since he was 18 is no big deal for him. It's not in his priority to get married it's yours. You might have choosen the wrong guy, not the wrong culture or nationality.
And some people's prejudice is showing big time and will continue to show. I understand being pro AA but understand that your culture came from those that you look down upon, at the end of the day we are all grouped together. Either get with the program and see how it can benefit the entire community as a whole when we unite or continue being the idiot that wants to divide.