K.B.
Hi-
I agree with Heather, but there's nothing you can do to make him "grow up" if that's the problem. My suggestion is to sit down and talk. Find out exactly what it is that is appealing to him about staying in that area. Is it the security of his mom being close, is it just familiar surroundings or is he scared about the financial burden that having your own place will bring? Find out exactly what he is thinking and then explain your concerns about staying. Once you understand exactly what you both want you can start looking for a place that meets both of your needs. Maybe neither the cousin's place nor the appartment that you have chosen is the right place. You need to compromise and get together on this decision. Maybe there's another mobile home to rent elsewhere that would give you your own home and a little space from his family but would allow him to not be in an apartment and to still be close enough to go see his mom when he wants to. This is just the first of many compromises the two of you will face in order for your marriage to work. Most things (especially big things like homes, cars, vacations, etc.) will never be exactly what either one of you want on your own but it will be a perfect blend of both of you so that you can both be happy with the outcome.
Good luck,
K.