Sadly, my idea was to get some centerpiece fish, because I was little bored of the Rummynose and Barbs. I was thinking that this pair will live happily, swimming together, following each other etc., but this is far from the reality. It seems that my tank is too small for pairs and their breeding behaviour. Probably I will return the male and get another female Gourami or another bigger female fish. Anyways thanks for the advice!You could get a large plastic storage container and put the male in that. Let him build a bubble nest and then breed them. After they have bred you put the female back in the tank and leave the male to look after the babies. He will care for them for about 1 month, after which time he chases males out of his territory so he can breed again.
If he doesn't get a chance to breed and look after the babies, he will probably be like this most of the time.