Getting married too soon?

Okay I'm a african amrican female, I'll be a college senior in the fall. I met an Ghanian back in March of this year. We are really cool and he's really nice. He was extremly ready to get into a relationship butI told him no,however he still think we're together. He just went back to Ghana for his sister wedding and now he's back in states. He said he wanted to date for 2yrs then get married now he said he want to get married next may...WTH? you guys I mean really this is crazy! I would just be graduating college and planning a weddin would be hectic. He seems to be extremly serious about this too. Marriage has always been shown to me as life long commitment an you shouldnt do it if your not ready. What should I say..???? Do people actually get married hat young?