Reading your topic I ask myself does she already have a Schengen visit friends or tourist visa? If not she has to wait until VSF global in Bangkok will open up. Some embassy sites (dutch, Belgian) say july 13th. Belgian embassy is not clear what visa they would issue suppose the date is correct. Also Belgian closed it borders to all NON schengen visitors (non essential trips). Italy did the same. Keep in mind that the list is an advice not a decision. The german embassy in Bangkok made it clear. No VSF global services for Germany until there is a regular flight schedule between Thailand and Germany. Dutch embassy states tourist visa /short stay Schengen visa are welcome. They will open on july 13th.
But the biggest problem occurs on Bangkok airport itself. I read several stories of Thai citizen still possessing a valid Schengen visa not allowed to fly to Europe because the airline staff stated they couldn't guarantee their return flight. This policy makes it almost impossible right now for Thai people to travel to Europa on a short stay Schengen Visa. My GF is the same situation. We don't take the risk right now buying a ticket and then ending up with a new cancellation. Nobody knows how long this situation will continue
Your other question marrying your GF in Europe and then trying to get a longterm visa is tricky. Some countries refuse to do a marriage on a short stay. In a few cases they warn the immigration. So it depends on the country itself. Perhaps the Begian or German route is still possible. I have no experience with it.
This is the link to the German embassy. Unfortunately it's in German language https://bangkok.diplo.de/th-de with the text in German "Bitte beachten Sie, dass Schengen-Visaanträge im Moment noch nicht bewilligt werden können, wenn aufgrund dieser Situation in den eingereichten Anträgen keine Rückkehrwilligkeit / Rückkehrmöglichkeit festgestellt werden kann"
Or in English :
Please note that Schengen visa applications cannot be approved at the moment, if due to this situation in the submitted applications no willingness to return / Return possibility can be determined.