Usually the females are greyish colored. This other gourami may be another male, but the one building the nest and has the pointed fin is definitely a male. Females are hard to find commercially since they dont sell as well as the colorful males.
I'm definitely no expert, but when you say he/she is building a nest.. I don't see it. I've done a lot of research on my pair and the male Gourami's build bubble nests at the surface of the water (similar to bettas) around floating plants. I've also seen people put floating plastic rings to help them deposit their eggs. They will do a dance (fish spooning
), female releases eggs, male fertilizes and then the male releases them to the surface. Something along thoses lines. They aren't the greatest parents either since they have been known to eat their off spring.