My Boyfriend Breaks Up With Me Each time we have problem. Right now he's asking Me to Marry Him!

I have heard so many sweet things about being in a relationship, things like, you'll have company, that one person will always be there for you with constant love and support, you will have another reason to believe in yourself, you'll always feel secured and many more. My own Relationship seems different.
Am Shantel, 22, a final year student, I've been in this relationship for 2 and half years, I love my Man so much and He loves me too.  He doesn't do anything without letting me know about it, we discuss about everything.

But the problem I've had since i started dating him is that when ever we have problem, he breaks up with me and after a week or less he comes back to make up. It has been like that in 6 different occasions and am so worried about it.

Recently, he asked me to marry him.

But am scared of what will be the outcome of our marriage in future.. I wouldn't want to marry a man who'll divorce me and take another woman..

I need an advice before i give him my reply.

What should i do?