In The Great Gatsby, what made George feel that his wife might have been having an affair?Chapter 8

Clearly we might infer that Myrtle's repeated absences
from their home in the Valley of Ashes might have aroused George's curiosity, however,
in Chapter Eight, after Myrtle has been killed in the hit and run, we see that what
really made George suspect something was when he discovered the dog-leash that Tom has
obviously bought for Myrtle for her dog in their appartment. Note how it is
described:

readability="8">

There was nothing in it but  asmall, expensive
dog-leash, made of leather and braided silver. It was apparently
new.

Clearly George knows
that, firstly they could not afford such an item, and secondly there would be no need to
buy something like this because they do not own a dog. It is this, of course combined
with the way that Myrtle reacts when she sees Tom in Gatbsy's car, that makes George
suspect that she is having an affair.