The fuel surcharge is there on SQ, yes, but it's absolutely worth it - especially if you can redeem for business class/first class. Most airlines will charge some sort of fees - SQ's is nowhere near the top in terms of how expensive they are on award tickets. Aeroplan charges ~$500-600 per one-way on Air Canada, Asiana and Lufthansa, for example. British Airways Avios is even worse!

My other suggestions would be to look at AA and the AAdvantage program, flying Cathay Pacific to Singapore via HK. They only charge 135K RT for FIRST class to Southeast Asia, though they do not allow for a stopover. Economy is 70K RT and Business 110RT. These are at the Saver levels, and are one of the lowest mileage prices available. With your 70K Citi AAdvantage card, you are already halfway there on for 2 Economy tickets. I'd advise getting Business or First class if you can, in order to make the experience feel all that more special.

Since you're in America, you can use the Citi AA cards to your advantage - if your fiancee and you get one each, that either covers the whole trip if doing it in economy, or one way in first class on Cathay Pacific - which is considered one of the world's best airlines. You could then use the Chase cards + Amex MR (Membership Rewards) cards to get enough points to come back using Singapore Airlines in business (or first class!) once you get enough points.