TL;DR: Read the last paragraph.
My girlfriend lives in Thailand and I live in Germany. We're both nationals of Thailand and Germany respectively and not of any other countries. I visited her in Thailand recently; now we're looking into finding a way for her to visit me.
Our long-term plan is for us to marry and for her to move in with me but we're not ready for marriage yet (we are ready for moving in together, though). As I understand the marriage visa ("Visum zur Eheschließung / Eingehung einer Lebenspartnerschaft"), it does not allow her to visit me simply on the basis that we are in a relationship, I can provide for her living expenses, and we want to marry at some point, but does instead mandate that the marriage is already planned and applied for. Please correct me if this is wrong.
She does have a university degree in biotechnology but as I have previously learned that university degrees of a different Asian country (Indonesia) do not have any basis in real qualifications, I'm not too sure whether that Thai degree is of any value for finding a job in Germany. Our plan therefore is for her to enter Germany without working in Germany.
In any case, she currently has a job in processing orders for a German chemical company at a branch in Thailand. She cannot take a lot of vacation time but she might be able to work remotely while in Germany. However, the way I understand the Schengen visa requirements, Germany mandates that employees be on vacation while visiting Germany. Please correct me if this is wrong.
If Germany does not allow her to work remotely, she will have to quit her job and she is willing to do so as she is not particularly happy with it. However, the info page about the visitation visa (https://bangkok.diplo.de/th-de/service/besuchsvisum/1372806) says "Beschäftigungsnachweis" (proof of employment), making the impression that in order to be granted a Schengen visa, she needs to have a job. Is this the case even if I send a letter of invitation saying that I'll cover her expenses ("Verpflichtungserklärung")?