Grammar fix
I'll get this
offer to pay
A friendly offer to pay the whole bill yourself rather than splitting it.
expressionB1common
Hear it in context
Notice where the phrase sounds natural.
Put your wallet away — I'll get this.
A: How much do I owe you?
B: Nothing, I'll get this — you can get the next one.
Fix the pattern
One small grammar move makes it sound right.
Not: I will pay this all.
Say: I'll get this.
The natural offer is 'I'll get this', not 'I will pay this all'.