Also i was told putting 2 males beside each other would cause them to flare at each other. Felix pays no attention to Romeo nor does Romeo to Felix. Also why wont Romeo flare? Felix flares alot at Jewel but Romeo has not flared since i bought him.
Why would you want them to flare? Flaring is due to the stress of seeing another male. By putting them in plain view of each other to try and get them to flare you're deliberately stressing them out.
Also, what happens if you LFS won't take them til they're old enough to sex? Then you've got a potentially very large number of males in the same tank until they're of a sellable size. What will you do with all those males?
It seems like it's going to be a lot more hassle than it's worth.
I'm confused about one thing though.. you've had this 2.5 gallon lying around? So that means the whole time you've been "forced" to have your gourami and betta in the same tank and we've been advising you to move one of the fish out, you coulda moved your betta into the 2.5 rather than buying another betta? Especially since it would appear your gourami's getting a bit moody with your older betta as we said would happen. I can't help but think that you've missed a good opportunity to separate the two fish here..
I also thought the new tank was a "guaranteed" gift? Personally I'd ask for it for christmas as planned and set it up slowly to lessen the immediate spending of money and get your gourami out of that 5 before it turns really nasty on your betta..