Why would you want to MAKE him agree, he should want to do this willingly. You also should want him to do this of free will so that you don't have doubts in the future about why he married you. This shouldn't be forced. If you have been together for a good while, 2 or more years, the shouldn't be any reason you cant sit down with him and have a reasonable discussion about your future plans and see what each of you wants out of the relationship. From there you should be able to make a decision that is best for both of you so your not further wasting you time on a relationship that will not be what you want.