My thought is they prefer retired people wishing to stay an extended time to apply for the retirement visa. They'll make it hard on you to try to do otherwise.
Get a non-immigrant O for 3 months, or come as a tourist 2 months and extend for one. You can only get 3 months away from her. If she comes to thailand within the 3 months, and you are on a non-immigrant O, you can apply for a marriage visa for a year. If she doesn't come, you have to leave after 3 months for a while, then re-enter.
unfortunately, yes, these were all potential red flags, as well as any border runs without multiple days in other countries. It looks like a lot of scrambling to figure out ways to stay in the country, rather than anything completely legit.
Thank you for posting. We all need to hear this info. 🙏 I definitely plan to leave every six months. Please let us know how the re-entry goes: which port of entry and if there were any questions. Have a good holiday! Penang Malaysia is fun and delicious if you need a cheap, closeby recommendation. Siem rieap Anchor Wat is a jaw dropping piece of history standing close by as well. 😃