Hi, I'd like to help you with your questions.
It sounds like from what you said that there is something about your relationship that you are unhappy with and that you think would cause enough of an issue that the relationship is or would be greatly affected. You also believe that your partner cannot accommodate your needs.
From what you said, your partner seems very willing to work on whatever issue is between you. Without knowing what that issue is, it is difficult to address your concerns directly. However, given that your partner is working with you on this, that is a very good sign that the relationship can work. The concerns greatly increase if partners are unwilling to face the issues or work on them together.
I would highly suggest that you both go to couples counseling and work on this together. People can change and they way you can tell this is if the person will work on an issue until it is resolved. Having a counselor there to help guide you both to a good resolution is a great way to work this out.
Also, it sound like there is some issues of trust or possible hurt in your past that may be interfering with your ability to see this as a resolvable issue. This is a guess on my part, and I chose to throw it out there to give you something to think about in case this is the issue as well. Resolving any issues now will give a you a very strong foundation for a good relationship.
I hope this has helped you,