Sure hoping someone can answer a Gourami question...

Males are slightly larger than the females and have a bright orange-red body with turquoise blue vertical stripes that extend into the fins. The dorsal fin of the male is pointed in contrast to the rounded dorsal of the female. Females remain a duller silvery blue-gray color, never achieving the brilling colors of the male. Several color hybrids exist, including Blue/Powder Blue), Neon, Rainbow, and Red/Blushing. (http://freshaquarium.about.com/cs/anabantids2/p/dwarfgourami.htm)

Once the nest had been built the male will begin courting the female, usually in the afternoon or evening. He signals his intentions by swimming around the female with flared fins, attempting to draw her to the nest where he will continue his courting display. If the female accepts the male she will begin swimming in circles with the male beneath the bubblenest. When she is ready to spawn she touches the male on either the back or the tail with her mouth.Upon this signal the male will embrace the female, turning her first on her side and finally on her back. At this point the female will release approximately five dozen clear eggs, which are immediately fertilized by the male. Most of the eggs will float up into the bubblenest. Eggs that stray are collected by the male and placed in the nest. Once all the eggs are secured in the nest, the pair will spawn again. If more than one female is present in the breeding tank, the male may spawn with all of them. The spawning sessions will continue for two to four hours, and produce between 300 and 800 eggs. Upon completion, the male will place a fine layer of bubbles beneath the eggs, assuring that they remain in the bubblenest. At this point the female(s) should be removed from the tank.(http://freshaquarium.about.com/cs/anabantids2/p/dwarfgourami.htm)

And yes, they will build bubble nests if there are no females in the tank. Some may think that there are, but there might not be.

Females are smaller and silver. Males also have a bump on their heads that the female lacks. Males will build nests without females as we all know bettas do.