You should have no problems cycling together, regardless of differences in strength.

I cycled three miles with my daughter on Sunday. She is 4 years old, 3 feet tall and her bike has no pedals, but there was no problem in us cycling along together. I also go on family cycle outings with my wife who doesn't cycle much, it's nice to take it easy an ride at a relaxed pace with her.

If you are trying to get vigorous exercise you may have a problem, but for a leisure ride there won't be an issue.