All dwarf gouramies are the same species regardless of color - that is, they are
Colisa lalia. Besides, females never posess the bright colors males do regardless of the variety (color morph) they belong to.
Gouramies don't form 'pairs' like, for example, some cichldis do. They only 'pair' for a very brief period during spawning - afterwards the male chases the female away and, before that, he acts pretty much as you are describing now.
In other words, what you are describing is perfectly normal - male dwarf gouramies are territorial and willc hase other goruamies away. When the other gourami is a female, he may also want to breed with her. Unfortunately, whereas males are always ready to breed as long as they are in good condition, females are not.
While this is normal behaviour, it's not a good thing for your female to be exposed to - in the wild she'd be able to escape the male's constant harassment whereas in a tank, she cannot. The first thign to do is to plant the tank mroe heavily - particularly with very tall and floating plants. This both gives the female a place to hide/get away and makes the male feel his territory is more 'secure'.
Next I would suggest that you lower the temperature just a tad but very, very gradualy and not below 76 deg F, as the higher the temp, the more active and aggressive the male will be (and the more likely it is that he feels like spawning). It's also a good idea to ensure both fish are well-fed and feed them at seperate ends. Remember to supply some veggies too!
Idealy, you need to get another couple of females. If you only just got this pair, just one mroe female is fine. However, if these two fish are established, you need to add two more so that the aggression directed towards the 'newcomers' is devided and, therefore, less severe. Adding more females will meant he male's attention is split so that no single fish gets the bulk of his chasing and this'll reduce the stress on the female(s). This is similar to what African cichlid owners do when they crowd large numbers of aggressive cichlids together so that the aggression from each fish is directed to more than one indivdual and, so, becomes 'subdued'.
Gouramies shouldn't be kept in pairs - unfortunately many fish shops sell them as such
. With dwarfs, this is particularly important because they so easily become stressed and that almost inevitably leads to illness - and being susceptible to severe internal bacterial infections, dwarf gouramies can quite easily die as an indirect effect of stress.
BTW, what size is your tank? If it's not 20 gallons at least, you'll have tor eturn one of your fish instead of adding more females as you won't have room for so many.
