Everyone thinks natty gut is soooooo fragile. This just shows, that multis are way more fragile than natty gut.
Especially the Thermo Gut coated Babolat natty gut is very durable.
My advice:
1. Start using a thicker 16/1.30 gauge of the multi. This will add some extra durability
2. Try using another multi. Babolat Xcel Power 16 gauge is pretty durable for a multi string and plays way better than NXT in my view
3. Start using Babolat Elastocross strring savers. I use 48-60 in all my setups. This will stiffen up the string bed a bit circa by 3 lbs extra tension - so string 2-3 lbs looser, when you intend to use string savers.
You will be amazed of how much longer life you will get if you use string savers - I get 5-6 hours without stringsavers, and 12-15 hours with the use of string savers.
4. If 1-3 do not work, then stop using a multi. Multi strings are not that durable. Instead go for a soft poly like Signum pro Hyperion or Tecnifibre BlackCode and hybrid that with the Babolat Tonic+ natty gut.