Your wife, on her bike, has a one-hundred pound advantage over you, on your bike.
She can out-accelerate you, she can out-brake you and she can out-climb you.

In my opinion, you can try any combination of three things:
-you can lose weight;
-your wife can gain weight;
-your wife can carry one hundred pounds of ballast with her, on her bike.

You asked if a larger diameter drive wheel would equalize things.
No, no it won't.
Just mounting a larger-diameter wheel in place of the stock wheel
will only change your gear ratio: you would be pushing higher gears
and life on your bicycle would be even more difficult for you.

Good luck!