Can I stay out of Thailand for six months on a retirement visa?

Just make sure you've got a multi entry or single entry Permit every time you leave the kingdom

Why don't you get a marriage visa?

You'll have to double check, but I think DTV allows to enter and exit as many times as you like throughout the year. There would be different ways to get it, but using it as a kind of culture oriented visa, taking thai cooking classes, traditional boxing or others (I don't know: potery, thai massage, traditional dancing, maybe even a buddhist retreat at a Vipassana centre near Chiang Mia or Rai, etc.). If you don't plan to work, it can be valid for up to five years, the money in bank required and price for the visa might feel realistic to you, I don't know. I was aiming at this visa for remote work, but do not know so much information with certainty, so you'll have to make sure every precious piece of information makes sense and is to your advantage. And I believe you can stay up to 180 or a few more days in a row with this visa. After that, you have to exit to any SEA country or other, come back if you please, your passport still has to be valid, they might ask for proofs of funds, but if you inquire before exiting and coming back, maybe they could also ask for criminal record and health related infos when you come back, so better investigate those aspects before leaving the country. I feel like there's lots of "if" here. The is also visa O. If I understand well, the first time you get it (and it's rather cheap), it's good for 90 days. After, you can renew it for a year. They might ask questions and proofs related to your savings, criminal record and health state, and I think there is a possibility to ask for that one year visa several times from Thailand. DTV: you'd have to apply from another country, be it your own country or anywhere near in SEA for your convenience. Good luck!

You can leave Thailand for as long as you want with a retirement visa/extension but you must be back to renew before it expires

Consider staying only 179 days to avoid becoming a Thai tax resident. That happens if you’re here for 180 days…cumulatively….in any calendar year.

With a retirement visa, there is no obligation for number of days in or out. You can stay inside for anything betweek 0-365