I would say the women in most cases always work harder than the men. I would agree that in larger ergonomic communities such as BKK there is a changing culture and more middle class. How long have you been in Thailand? You did say they (gf and family) don’t expect you to pay for everything. You shouldnt have to pay for anything except as a gift.
I think you will find, and please ask your girlfriend about lending money to Thais. Even she I am sure will tell you to be careful. As per this post it has nothing to do with who pays who its about lending money within the Thai culture. Treat it as a gift expecting no return and you will be ok. Bartering is something also completely different. There is a reason it takes a longer to close most larger deals in Thailand (land, cars, boats etc). I’ve seen it on every front but shouldn’t be considered derogatory but part of the culture. Those of us who live here just except it and play along and have a good laugh. Thailand is still one of the best places around.