Re: will this motor work
A 25 would deffo be better, once again as its long enough.
But it appears to me that the problem and what you are trying to correct is the wife's fear of the water or boats in general.
I had the same problem years ago when I married and had a bass boat. She was terrified from the start because she had had never been out on the water and was 35 years old. So I helped her feel confident and this is how I did it.
Everyone wears a life jacket, no exceptions, all the time while on a boat.
First rides stay close to shore and keeps speeds minimal.
Be confident, never show signs of indecision and keep conversation other then what you are doing constant.
New riders fear bow rise on accel, they dont understand why this is normal.Minimize it as much as possible.
Might take a few rides for them to get somewhat comfortable, but once again, she is going to be looking to you for security and comfort.
Then again, some folks just never take to boating. Its a lot of confidence and adventure to trust a hole in the water to keep on floating until you place your feet on land again.
Hope this helps.