I been there. My wife has been riding for the past 2 years. And she significantly faster, actually a lot faster. Never adapt to her speed, I would do intervals and dial it up and would slow down and she would eventually catch up. I have routes we do and have it programmed on her cyclemeter app and as time went by, she saw a lot of improvements. Our favorite route after work is a 17 mile route we do 3 times a week. Her first run was about 14mph average and now she's averaging about 17-18. When we go to the bike trails, I set up rendezvous, I just tell her ill wait for her at the spot. One thing I never did, is I never forced her to ride. She wanted it on her own. And sometime she goes out solo. 2 years later and 4 bikes later, last one being a S-Works Amira, quite a few metrics. 20 pounds lighter. She's Hooked! Set small goals for your wife, believe me if she sees improvements, she'll stick to it.