The Harem storyline is such a minor part of the books. Rand only sleeps with Elayne and Aviendha from memory one time and two times respectively, Min is the only he sleeps with on a regular basis.
Personally I think that the idea that a couple is the best relationship dynamic for every person on Earth is shortsighted and has to a large extent been forced upon us as traditional by religions that are far too interested in our sexual activities. As long as the relationship is safe, sane and consensual I don't really see why any number can't make up a healthy relationship.
I was okay with the show giving a more physical relationship between any of the Avi, Min or Elayne, but for Avi and Elayne it would require some changes especially in regards to the rebirthing ceremony.