Never been asked. But cash is king. Credit cards with no transaction fee is how I pay for hotels. Last resort is a debit ATM. Most people convert their currency to baht after arriving. (Not at the airport because the rate is a bit higher). Convert enough for a couple days worth. You’ll find conversion places all over. Get some 100 baht bills for taxi cabs.
Getting a Thai girlfriend a visa is difficult. They want her to have a good job, a letter from her employer, a bank account . Someone who will actually fly back to Thailand. Do it right the first time and she’s good for continued trips. Screw up and never again. Another option is you have to apply for her 90 day marriage visa. You apply from the USA she will get an interview in Bangkok…….