Very likely males and also males of the Gourami varieties fight and harass each other and one or 2 will likely die.
It is hard to believe, I know, but they only want one male around to be the dominant fish for the territory. Sometimes when 2 fish are raised together they may be chill if there are places to hide or is one isn't especially dominant or if one is a female.
I even had one Pearl Gourami from a group of 2 males and 2 females supposedly would get along, kill the other male and a female. He got rehomed to a semi aggressive tank and lived his own life minding his own business nicely for a very long time. Even someone gave me a couple Dwarf Gourami which were raised together and I guess were both males, I didn't know the difference at that time. One killed the other.
Bottom line, when they begin reaching sexual maturity and are looking to have a female to mate with, they tend to get dominant to claim their territory.
And when you have a smaller sized tank, there isn't anywhere for the less aggressive male to go, like in nature, where they can find somewhere outside of the other's space.
If the fish store thought it would be a good idea to sell you a bunch of Gourami males, it was very poor advice.
What size is the tank?
New to FW fish? First tank in a long time or EVER??? Need some info on keeping fish?
Start here - Aquarium Advice Article
FW Favorites right now Clown Loaches, any shrimp - SW Vase Red Mangroves