I took SCUBA diving as a PE credit in college but never got certified either. Didn’t have the funds for the winter trip to Florida and I was the only female in the class....
One year my husband and I were looking at going to one of those all-inclusive resorts with a group. He’s not a drinker and I can only lounge for a day before getting ancy. I did notice that shore dives were included in the resort.
We never made it to that resort, but both my husband and I are certified and he went further and got his Dive Master certification.
My favorite dive was a shark dive through Stuart Cove in Nassau. Second wan on a live aboard in Palau.
Hopefully your wife would want to join you one day. Our adult daughter has no interest in diving but she will snorkel.
Check out Advanced Certification after your cruise. You can get extra training on buoyancy control.