This is a legal question about real estate. Since we are not attorney's our answers will be limited, but if in doubt, discuss this with an attorney who does estate work. It may be as simple as setting up a will to pass the house to your wife in the event of your death. As long as the payments are made, I doubt the lender will care. It may be useful though to send them your written authorization to speak with her regarding the loan. That way, if you are injured but still alive she can talk to them if necessary.
Estate planning is a very important step when you have a family and any assets. I used to hear an attorney on the radio say, "If you don't have a will of your own, the state will prepare one for you." The message is that the State's will may not meet your wishes. Better to be safe than sorry.