I'm not sure if your loan is an FHA loan, or if both of "we" were on the loan and you'd have the financial ability to do that. But if you wanted evidence in writing that is all that is required, see:
FHA Requirement for Establishing Owner Occupancy
At least one borrower must occupy the property and sign the security instrument and the mortgage note in order for the property to be considered owner-occupied.
FHA security instruments require a borrower to establish bona fide occupancy in a home as the borrower's principal residence within 60 days of signing the security instrument, with continued occupancy for at least one year.
Like some of the others have suggested you should have a way out of this if you have a circumstance where you have a "need" to move. Another attorney that you could contact is
John D. Carver, Esq.
Carver Law, LLC
600 Seventeenth St., Suite 2800 South
Denver, Colorado 80202
Tel: (720) 932-8510
Fax: (720) 932-8509
I've worked with him and he's excellent and won't price you out of the water as some attorney's do.
Feel free to call with any questions. Once again I'm sincerely thankful to hear of someone doing the right thing even though it may be harder up front it'll pay off in the end.
Keller Williams Realty
All of these are good answers as to your need of a good real estate attorney. Before you go to the attorney, however, you should also have all of your ducks in a line.
That is, you say you "need to move out", but what is the reason? If you just "want" to move out, that puts a different construction on the problem than if you need to move out because of a job transfer, health reasons, additions to the family that make it necessary for you to move into a larger home (for example, triplets born after the loan was made), or some other such thing. Have all of your documents in order, so that the attorney will have a clear picture of your agreement with the mortgage company.
As Scott said, by requesting a waiver of the occupancy requirement, you have put the mortgage company on notice, and you must act accordingly. Don't delay -- stay put for right now and get in touch with a real estate attorney right away. Find out if there is any way the attorney can negotiate with the mortgage company for a modification of your loan based upon your "need".
Here's one excellent real estate attorney: Cyndi Lyden at Rumler Tarbox and Lyden, (303) 333-7733.
Tracy Howard, CIAS, CDPE
Broker/Owner, Distressed Homeowner Headquarters
You will want to first pull out your loan documents and then contact a real estate attorney. They will need to see what you have signed and what the terms of your note are. If you are in default with any of these terms then the lender does have the right to call the note due. You may want to explore either selling the property or refinancing the property into a non-owner occupancy loan. Non-owner occupancy loans typically have higher interest rates associated with them and may require more loan to value in the home. Either way don't rent the home out until you have spoken with an attorney and explored all of your options.