In my first community aquarium, back in early 90's (before widespread internet and information) I had a betta with some dwarf gouramis and some other, common LFS stuff, too.
For awhile everything was fine. One day, one of the dwarfs was dead, the next, a second was dead, and a third had his eye trailing alongside its body. It died later that day.
I then went to library did some research and learned the two don't mix due to being in same family/genus or something. Do not do it.
55 Gallon, planted
Cherry Barbs 5
Porkchop Rasboras 7
German Blue Rams 4
Boesemani Rainbow 2
Siamese Algae Eaters 4
3 Lined: 1
I think I am pushing it, but water quality is holding up fine, and all the fishys seem pretty happy.