If it is the same two fingers it is deffinately due to the fact that she uses them for some task regularly, you need to find out what she does as a job etc.
I had a couple of people with similar problem when i have used tips, but i have sculpt those missing nails during the repair and they were fine.
Here is a little story I had to deal with :
I had a client once, in fact she is still a client, but a better behaved one now))) I would put a full set on, she would go away and come back in 3 days after with no nails on and the natural nail would be shiny! I have tried to find out what she was doing in these 3 days and she would say - nothing out of the ordinary! I would reapply the set (free of charge of course) and the same will happen 3 days later.
I have done a number of free sets on a number of occasions, dehydrating the nail more, using nail fresh and more primer, sculpting instead of tipping, tried it all and she was still coming back with no nails and het natural nails were shiny like there was no enhancements on at all.
To put a long story short - one time during a service she told me betwen the lines that she was using AMMONIA to clean her house every day with NO gloves. Obviously ammonia was eating away the natural nail slowly hence the shine.
Now I make sure I let them to be aware that they follow the recommendations to avoid service breakdown, clients tend to think they know better and they will almost never admit they have done something wrong.
hope this helps)))
