i get it, but i say..

the number is supposed to be 1.9(9 repeating?)


1.99999... is 2.

0.111111111.... = 1/9
0.22222222.... = 2/9
.
.
.
0.9999999.... = 9/9 = 1


Then the bartender didn't pour enough beer. It is not infinite.

You are right in that in the real world the division will stop at one molecule, but the realm of mathematics is abstract so we treat the beer like a continuous volume, infinitely divisible.