I will throw this out there... First time in SE Asia, want warm, calm water, only two dives a day, see another side of life in this area?
Instead of northeast Bali, finish diving at Padang Bai and take a fast boat to Gili Air. The boat ride versus a car trip on a crazy truck-infested highway will take you two hours instead of four to five. The water is warm and current minimal most of the time. Although the coral will not be like Menjangan, you will see tons of life including more turtles than you can imagine, sharks, fish galore, and all the usual macro suspects. The dive shops usually do one dive, come in, and then repeat. If you decided to add a third dive, you would only be gone a short time and your wife would not be bored on shore.
Topside Gili Air is magical...at least I think so. There are no cars or motorbikes- only bicycles. The beaches are white sand, and the snorkeling and SUP opportunities are awesome. There are a number of restaurants and bars, but not enough going on to attract the real party crowd. It is by far my favorite place to take my friends and family who come to visit.
Do some googling and see what you think