What are the financial requirements for applying for a DTV visa in Thailand as an unmarried couple?

You each need your own money, your own paperwork, your own everything. There are a number of consulates that don't require the money to have been in the account for any particular length of time, even though they ask for 3 months of statements it's the closing balance of the 3rd month that's important

Thailand is an Asian country where couple only means legally married ones. Any other explanation is useless. However, bank statement money can be stored for a few weeks only, that's ok. You don't have to maintain it for 6 months.

Being that you are not married, you are treated as two completely separate people, having no relationship at all. You both need your own bank account with bt500,000+ in them. It doesn't matter what explanation you write. You are not married so treated as complete strangers, with each of you required to meet the financial requirements separately, with no exceptions. You should get the DTV for yourself, and while your partner's financials season in a separate bank account, enters on a 60 day visa exempt entry, so you both stay together. With the 30 day extension that can be taken, this puts you at three months of bank account seasoning. There are thai embassies that accept 3 months of bank account seasoning, and basically every embassy except those in Vietnam accept three months of the bt500,000 being in the account. Manila in the Philippines, from the last reports, accept just 30 days of the money being in the account. Taiwan also.

Irrespective of the relationship each person requires the 500k

well if you're not married they're not getting a DTV based on "family of a DTV holder" that's just how it works out. They're going to apply for a DTV on their own and you having a DTV and being their un-wed partner isn't going to make a difference or not

Now as far as the sponsor letter saying you'll cover the proof of funds, you'd probably have to show that you have the funds for your DTV and for hers (so 1 million baht in the bank) BUT that's just a guess and I could be wrong

Unfortunately, you are not viewed as husband and wife. Theodore, one of you couldn’t apply as a dependent (spouse or child of the other). You would both need to apply separately, meaning both of you would need to meet either the digital nomad or the soft power requirement and both would need to have the 500k. They only allow sponsorship letter (usually) when it is a dependent (married or child)

back in june, in Jakarta, i provided a free-form sponsorship letter (like i am father and husband, and i guarantee to support financially my wife and daughter).

i applied first, they issued dtv for me. then i wrote this letter and we added it to my wife and daughter's applications.

Hey are very strict about the 500k.

Maybe a sppnsorletter would work but i think it require a family member, and not beeing married it could be a problem. Buy depends if the embassy employee is in a good mood i guess. Are the rest of your and girlfriend paperwork strong?