Fantasy, Sci-Fi, and/or Action book recommendations without love triangles?

Anne McCaffrey's Dragonriders of Pern series has romance. I don't remember if there are "love triangles" but if there are they are not main themes of the books. The first one is Dragonflight. I liked these books alot. Piers Anthony's Xanth books are fantasy/sci-fi and have some romance throughout. I don't remember love triangles. These switch characters though. I liked them a lot too. The first one is A Spell for Chameleon. It wasn't the best one, but it was still good. The one I read first was Dragon on a Pedestal.