I have been reading quite a lot in internet and here but despite all the information in this amazing community it seems like I can't find the right answer suitable to my case. Some details to complete the picture:
I am Spanish, holding an S-Pass (over $6K a month). I have been living in SG for 3 years already. My girlfriend is Thai, I met her 4 years ago has been living with me almost all these 3 years under a student pass. Before I traveled several times to visit her and travel together on holidays (prior relathionshio). She has studies in accountancy (BKK university) and currently finishing a higher diploma in Hospitality and tourism management (SG academy).
She is currently holding a Training Work Pass, and just started her 6 months industrial attachment or her studies in SG.
In 6 months her training and studies will end (low chances of getting hired) and we would like to find a job for her to stay in SG and we dont really know what is the best way to go. We are not married, but of course open to it, despite we were originally planning to marry later on. Please correct me if I am wrong on the following assumptions.
LTVP requires a "Common law marriage". I have read that even living together in SG for this long we can't get this done in SG (as they don't reconize any premarital relationship). Correct?
If that case we would need need to do this in Spain. We could prove we have been living together this 3 years and our relationship before that. What do you think are the chances of getting an LTVP approval if we follow this way?
DP would require that we are in fact married, in this case, what would be the easiest way to get this done?
Can we just marry in SG while she is here so the ICA could easily check our marriage and shorten the process?
Do we need to do this in Spain and then prove our marriage status to ICA in SG? (This would be much more steps to go...)
Anything that could be possibly done in Bangkok?
Finally, considering our specific case, any recommendation of any alternative to get this done without getting married? this would simplify the bureaucracy, as well as make everything easier culturally (her family might not understand we get marry in a rush like this, and we would prefer to do it later on in the "right way")

As you see quite a lot of questions! thanks so much all in advance for your guidance!