I agree with Liquid Skills, no Betta with Gouramis. He's probably get torn up by a Blue or Opaline Gourami.
I keep a Pair of Pearl Gouramis with a single female Opaline and they get along fine. They might not if the Opaline was a male so I wouldn't suggest adding any male Three Spot Gouramis to a tank with Pearl Gouramis in it. As it is my Opaline female chases the male Pearl around sometimes and I can only imagine if that female was a male! I would also try to add a female Blue, Gold or Opaline that's a bit smaller than the Pearls so the new fish won't feel too bold.
BTW, if that's a 40 gallon "breeder" tank it's perfect for Gouramis! It has a very long footprint which is better than having more depth, like I have.