Gouramis are not schooling fish, don't know where you get that from. Natural behaviour for a gourami is for a male to establish a territory, into which he may let females enter but not another male. From this it follows that a single male will not be lonely. It is pointless to compare territorial animals like gouramis to flock livers like monkeys and humans (or tetras, for that matter), that's just bad science. Fish are as diverse in behaviour as mammals.
It is true that if you insist on keeping several male gouramis then you need to keep them in such a large group as to make it impossible for them to establish a territory. But why this preventing of natural behaviour should be considered kinder than letting them get on the way they'd normally do I really don't see.