See...for many of us it's clear that we can't be like Hamilton or Donald Trump or Onassis..we simply can't earn like them.. that's the life...
it's depend how your GF said that statement..maybe she even didn't mean anything bad really..try to talk with her about it.
I think that she didn't mean to insult you.
Me & my husband have a that kind of talk very often :) when see something on TV we start : Ohhhh when we will have all that? or I wish I could earn more money to make a house, buy a new fancy car for us and for our child..
but that is true :) we are aware how much we earn..but this statement doesn't mean that we don't appreciate each other ..
Anyway-Hamilton earn all his fortune by himself, by his own effort..no matter of his parents earning..
So..maybe one day your son will be able to earn much more that you both earn..it's our duty to guide our kids in their life to be more successful than us, to try at last to make them more successful..
it's enough for you to say that you are doing your best..you are at two works, you can pay your bills, your son have a home, security, love...it's really enough ..
So..how your's son life will be?!! no one knows..even and his own mother..
**maybe one day you will enjoy in his luxury yacht :) **