I thought more about this, the things I did other than dive, the things I would have done if I hadn't dived every day. You'll need to miss some of the dives I'd make to be with your girl...
You can catch 2 boat dives in the morning, then spend the afternoon with her.
You can take every 3rd day off to be with her all day.
Both of you sign up for the Anthony's Key Resort (AKR) Snorkel With Dolphins ASAP, as it fills up.
Both of you consider the day trip to Utila, Snorkeling with Whale sharks - or maybe you won't see any, but it'll be a nice day.
Do the island jungle tour together. Go to the remote northern town built on stilts together. Maybe even fly to the mainland for a day to river raft.
Yeah, y'all could do 2 weeks there. You can always entertain each other.
Now the shop managers are employees, but the boat crew may be temporary workers. If you can get one of the shop managers to take your girlfriend on a Discover Scuba course, that'd be nice. Robert & Willy were still there last summer; I'd trust either with my daughter, even though Willy is silly.
Oh yeah, take a couple of Maple Leave flags. 2' x 3' maybe. I had Willy fly a Texas flag from my boat, and I hung one from the balacony. I know you don't want to be confused as a Yank.
Do a Google Search of US State Dept advisories and CDC Advisories to have all the info. Take what you like, leave the rest.