Hi CC, and welcome to the forum
The fact you went on a single date is a good sign IMHO. It suggests she both likes you and trusts you not to ‘spoil her day’.
I think there may be a few factors at play.
a) She’s here on an EP and hence I’d expect is conscious that her time in SG in finite. She might be wondering whether it would be wise to allow herself to fall in love if she is not planning on being here for ever. Don’t know, just a thought. On which note, have you considered whether you would relo if you had to to stay with her? Either a x-posting elsewhere following her, or back to Spain? Have you reached a point where you can discuss such things [I’d quite understand if such matters would be ‘inappropriately long term’ at this point]?
b) Neither of you are spring chickens any more. You’ve likely been around the relationship block a few times. You’re probably both at a point where you feel it would be great if you could find ‘the one’ and settle down. So in her shoes this might be more than just finding another boyfriend.
c) Lastly, it’s hard to say as we have no idea what she’s like, but, to what extent might she be a ‘player’? Aka how straight does she run her relationships, vs you and her friends? Some people are as straight as an arrow and WYSIWYG, and at the other end of the spectrum are what I’d call players. To them it’s much more of a game, it’s not always one-sided sometimes both sides enjoy playing it. An example of that is the expression ‘Treat them mean to keep them keen’. That often comes across as playing hot and cold, and yes it can be very confusing, especially if you’re keen.
CC: ‘And the more the 2 of us talk about it, the more issues we know we will face.’
But another expression you will know: ‘Love conquers all’, and it’s really true simply because it is so powerful. And again I’d take it as a big positive that you’re discussing what are quite difficult matters.
CC:
‘As of now, both of us agreed to just let things take its own course. I am also apprehensive too due to society's biases on interracial relationships.’
Well sod society then. Proceed with the week assuming you’ll perhaps meet a person that might have a problem with your marriage, but who cares? IMO/E getting your respective families on board is waaay more significant. Not that you have to of course, but if you can then it's like a natural tail-wind. I’m in a X-cultural marriage, as is my sister. My aged parents are X-national but back then that was perhaps =/+ bolder and unorthodox that x-racial is today. There are several other people on this forum in similar shoes, so we know how it goes.
CC:
‘P/s: as if things are not complicated enough, she just drop a bomb on me. Her whole family is coming to Singapore to visit her soon. And she asked if i want to meet them....’
Lol! The baptism of fire – ‘Meet the parents’. This is another *major* positive, that she trusts you enough. But it’s also a test, as what her family make of you will undoubtedly influence how she concludes something longer-term with you might work. Winning over her parents is the primary hurdle of course

I’d find out the families interests then draw up a list of suggestions of what they can do (TripAdvisor/Top Attractions). Offer to take them on a couple of days out, be their tour-guide. Also offer to show them ‘real/hidden’ Singapore, stuff that isn’t in the guide books, maybe as simple as visiting a wet-market, buying fresh-ground spices in Little India, and taking them to East Coast for seafood etc. I don’t know if you know any Spanish at all, if not learn say a basic few dozen words. So you could help by suggesting maybe; ‘Are you ok with spicy/chili?’ – ‘The price is per 100grams’ and so on... words and a few phrases that helps them interpret the new environment, and shows that you are making an effort to help them understand your country and make their stay easier and more rewarding.
Good luck, I’m feeling positive vibes from you maaan
