Li Sean Loy you leave and return just before the OA expires..on re entry you get stamped on for another 12 months.. not sure what happens if you leave in the second year when the visa has expired though..🤔
After the end of the second year stamp you need to reapply for an OA visa again..outside of Thailand.
it appears that the easiest option is extension based on retirement as it carries all that the marriage visa does as it's faster and with considerably less paperwork ?