When I go on vacation my fish don't eat for 10 days to 2 weeks and rarely die.
The overfeeding and chemical waste buildup as stated by others above is more likely the cause.
I also agree feeding only one thing, bloodworms is not a good idea. Its like if you only had broccoli 3 meals a day for the rest of your life, deficient in vitamins and minerals.
And... dwarf gouramis are a very inbred/line bred fish and notorious for being generally weak, and having a compromised immune systems .
I was talking to a friend who managed a LFS about the weakness of line bred fish such as EBJDs and the like, he said when they'd get dwarf gouramis in, and they'd lose an average of 50% in the first week.