Not sure on that combo. I've got female bettas in with a female opaline gourami with no problem whatsoever, but in my experience paradise fish are much more aggressive than the other types of gouramis. If I were you, I'd get the rest of the fish in there and make sure the paradise fish agrees with them first. Then, assuming all is well for a week or so, try a female betta, and if it doesn't work out she can have the 2g hex.