If she is financially stable and has travelled to other countries without "incident" such as overstating, she wouldn't have much trouble getting a visitor visa. Her application has nothing to do with you unless you are financially sponsoring her.
My wife easily got multiple visitor visas to Aust before and after marriage because she was working full time and had travelled all over the world without incident.All she needed from me was a letter of invitation.
Partner visas are a long , expensive and drawn out process. Not worth it unless you are planning to live there together.
Tourism is dead in Thailand atm due to the baht being inflated and shit going on in many other countries. Add the extension of exempt from 30 to 60 days for most foreigners visiting.
. When did that stop because I did it 2 years ago. Non o ext->60 day family -> non o ext. I was 2 days short of required min bank balance and they actually suggested it at immigration to bridge the gap.
You may be able to get a 60 day " visit family" extension to bridge the gap but is only available if you have a Thai spouse or child, which you haven't mentioned.