Let's assume your GF's ears are healed, either now or in the future, but she still has trouble equalizing. This is definitely problematic in drift diving. In my first couple of years of diving, I did most of my diving in Cozumel, and I really, really, sucked at equalizing. I was so bad I had an instructor tell me that diving just might not be in the cards for me. Here is how I dealt with it on my annual Cozumel visits.
1. In the weeks leading up to the trips, I would gently try to clear my ears whenever I thought about it, like while watching television. I was generally unsuccessful at first, but eventually I would be able to get that "pop." Don't force it! Just keep working it gently. Be patient!
2. On the plane flight to Cozumel, I would do this repeatedly.
3. On the day I arrived, i would check into the hotel, which was right on the shore, and make arrangements for my diving. Then I would head for the water and start snorkeling. By that I really mean free diving. I would try to clear my ears and then descend as far as I could go without feeling pain. Every time I did it I got a little deeper. I could hear things opening up in time.
4. The next day I would work on it during the boat ride to the dive site. I equalized just before rolling into the water and immediately before descent. I would be a little slow equalizing on the first dive, but I would usually be OK on the second dive.
5. On the second day I would be much, much better. By the third day, I could equalize as fast as I could descend.
Today I dive frequently, so my ears are totally accustomed to it. I barely have to think about it. That's all it really takes--doing it a lot.