I've got a pair of pearl gourami in a 30g community, and they seem to have gone into spawning mode. Their colors have gotten more intense, and the male has built a bubble nest in the quietest corner. They dance around every once and awhile. This alternates with violent chases and with quiet hanging out in the ambulia (under the nest). The rasbora, who also like the ambulia grove, are periodically chased off.
The nutshell end of the story is:
•How big is the tank? (How much room do you have for violent chases? can harassed fish get far enough away?)
•How much coverage will harassed fish have available? (Her best coverage in my case is unfortunately right under the nest. Plants, driftwood. She made an escape move behind the heater at one point).
•What other fish are going to be effected as bystanders? (The two schools of rasbora have fused back together and seem a little freaked out: they liked having long swims back and forth).
It also depends on the temperament of the gourami: the pearls are supposed to be one of the most peaceful gouramis. And usually they are, but today they're not.
I've heard of using two females with a male to diffuse aggression, but when he pairs off with one the other one may be harassed by both. Part of the pair-bonding bit. I think having an "other" actually helps reinforce the pair-bond, which may be better for breeding. (Think high school).