Women engage to marriage for many reasons: to feel secure, to have kids with particular man, to have social status of a married woman, because of love, to lessen social pressure from relatives and society as an unmarried woman, because they were told it's right to do so. Those all are different reasons, women separate them, I just asked some women why they could marry someone, talked with a psychologist about that as well and that what I've got in response.
I wouldn't dare to think I definitely know why one or another woman decided to marry me.