Beautiful, just beautiful. I did a double take on the opals, nice going, I love a surprise detail like that, don't see them enough, IMHO. It works well with the whole design and stone.
Congratulations, love to see outside pics too, if you have any!!!
I do not think the opals will pose a huge problem, they are small but of course she should not have the ring on when doing heavy cleaning with bleach, etc. This only poses a slight risk of losing the ring but unless she has a job where she works with hazardous fluids, she would only have to take it off at time when using extreme heat and/or cleaning solutions and she can find a place for that. I do have to say that it personally drives me crazy when I remove my ring because I often have no clue where I left it, so maybe find a place for it at home.
As to cleaning, I clean opals in an ultrasonic but I just use the general, home ultrasonic, a cold-water version and anyhow only use JAR detergent mixed with water in it, which does not hurt the opals. Opals like water, they hate dryness and heat. Yes they can be very fragile like pearls but less so than many people think. I would be concerned if the main stone was an opal but not about these tiny stones.
If she does not want to take extra precautions like many of us gem nuts do, then yes they can be replaced later. Like I said they are well protected in the setting and smaller, so be happy and hope your significant other will absolutely love it. Congratulations!