I think the writers shipping He-Man and Teela really didn't work once the "Prince Adam with a secret identity" concept took over.
It's not even unique to Filmation, where they'd want to downplay it because the main audience was preschool and elementary boys. The 1982 DC Comic had Adam with an unnamed floozy on each arm. In 200X, they're 4 years younger than Filmation and Teela's teenage girl contempt for Adam is palpable all the time.
Psychologically, they're practically siblings (and Teela says so in the Filmation ep "Into the Abyss").