
that is sad
If you didn't notice that the fins were gone when you got them the other one might have bit them off. This is even more possible considering the chance that you got a pair of the same one. This is what I think happened
1 you bought both fish and brought them home
2 one is a male one is a female
3 the male is being rough on the female because he wants to mate and she's not ready. (this is where the fins probably got bit off).
4 the female dies from the combined stess of the aggressive male and recent transfer.
I still think you should stick with the gouramis, return that naughty boy and get some females-- you can tell them apart by the shape of the end of the fin on there backs--the males is extremely pointy and the females have rounded ones.