When two characters share a love interest, a love triangle is formed.
Season 1
There were no obvious love triangles in Season 1, but since Laval and Eris have possible crushes on each other, there could have been a love triangle between Laval, Eris, and Rogon.
Season 2
The main love triangle in the second season was between Crunket, Lavertus, and Crominus. Both Crominus and Lavertus loved Crunket when they were young, and Crominus was so jealous that Crunket loved Lavertus that he got Lavertus to steal Chi and get exiled.
There was thought to be a love triangle between Eris, Rinona, and Rogon, but Rinona was Rogon's sister all along so there was never actually one.
Season 3
The main love triangle in the third season will be Li'ella, Laval, and Sir Fangar. Laval and Fangar will fight for the love of Li'ella.