Having recently watched Eddie Kendricks Unsung, as well as reading several books on the Temptations; was their affair really just some short, term fling or was it alot deeper than that?

The reason why I ask is according Eddie's daughter they started dating during their Prime and Primette days, which was well before they joined Motown. However, years later after Eddie had married, which was 1965, Diana Ross was still turning up at Eddie's place causing a commotion. Was it some on and off affair? And why was Berry Gordy so angry over this particular affair, when Diana had relationships with Smokey Robinson and Eddie Holland?