I started a gourami tank a few yrs back and began with 2 blues. The bigger blue chased the smaller non-stop . As I added more; pearls, golds, platnums, paradise, the big blue stopped alomst completely other then a few false charges. As I slowly got larger fish I started to move a few to a different tank. I eventually got down to 2-3 Gourami's and the Big blue started up with the NON-STOP chasing. When i finished moving the rest (the big blue) into the other tank with the rest, he stopped again.
they are schooling fish so getting rid of one isnt the best thing you could do, and making more cover will help but there natural behavior will make the weaker one keep coming near the mean one.
If you have room by a couple more.