Dwarfs are fine as long as you don't keep them as pairs (as you know
).
Three-spots are a different matter altogether. There are a few things you can try before resorting to seperation but that may well be what's necessary. Also, if they breed (three-spots spawn very easily), the male could (and almost certainly would) start attacking and killing other fish in the tank as well as bullying his gourami girlfriends.
First, lower the temperature in the tank. High temperatures encourage aggressive behaviour. They make gouramies feel more in the mood for spawning and they become mroe territorial and more interested in the females. As fish are cold blooded, increasing temperature generaly increases activity levels as well (don't worry, you're tank's not going to come to a complete halt just by lowering the temp. a few degrees!). Make shure you do this gradualy so as not to shock anyone and don't go below 76-77 deg F.
The next thing to do is add floating plants - lots of them. Tall plants also work if they are high enough to have leaves floating at the surface. These will encourage your male to establish a small territory which the females can simply avoid. Obviously, he'll still chase them around, but the problem should be less severe.
This should be re-enforced by increasing the current at the water's surface. It need not be a lot - just enough to discourage even the idea of building a bubblenest. It'll also drive the male to stay in the part of the tank with the least current (which you need to make shure has its share of floating or tall plants). The male should preffer this area and spend most of his time defending this area.
Something else that can help is just to generaly re-arange the tank and/or add new ornaments. This confuses the fish, making them think they are in a new place and they take some time to re-establish hierarchy etc. However, this is only a temporary solution.
Another thing you can do is add some new, active fish, such as danios, smaller rainbowfish or non-nippy barbs. These will distract the male (though, again, it'll probably only be temporary) while he tries to defend his territory. Eventualy he'll get sued to them, however, and their presence will stop having any effect. Also, this can be a little risky as some gouramies respond differently to others. He may actualy end up more aggressive and violent towards all his tankmates rather than focusing on preventing these few quick little fish from invading his space. Also, obviously, you need to treat these fish as tankmates in their own right so they need to be researched and something you like. If you don't have room for more fish, this isn't even an option.
If you see no improvements after trying a few things, you're simply going to have to seperate them. Mind you, 3 females may also not work on their own. If this proves to be the case and provided you have room, adding 2 more females of the same size as the existing ones should solve the problem.
I have a dwarf gourami and he is agressive don't want to let him go just keep hoping he will change some day (he actually bullied and killed his female mate 
) Lots of people are lucky but noticed there has been a few topics on agressive gouramis but most seem peaceful so I guess I was one of the unlucky ones 
