Technically, everyone has their own decision on shipping base on their reasons. Yes, I'm one of those who ship Nalu and Gruvia since Hiro Mashima seems to be supporting these pairs by making big moments between Natsu x Lucy and Gray x Juvia throughout the story.

Probably people ship Nalu not just because they hugged. They are the closest of the guild, which some members of the guild like Mirajane or Cana teases Lucy about her relationship with Natsu. May or may not to you, but people ship Nalu because Lucy may be having a secret crush on Natsu as she is always concerned of him and the latest christmas omake shows Lucy having an affection to Natsu when she got drunk.

For Gruvia, it's true that Juvia is so clingy to Gray which most of the Gruvia fans like to see. Gray does seem to like Juvia as he can see Lyon trying to get her which makes him jealeous. However, some fans say Gray doesn't like her, or it could be a possibility Gray likes her but doesn't take his relationship with her too seriously like Juvia does. Finally, Silver Fullbuster (Gray’s Dad) considers Juvia as Gray’s woman.

Anyway, that's how I could answer your question. These are just probabilities of reasons why over 90% of fans ship Nalu and Gruvia to you.

While I perfer other couples then Nalu and Gruvia (I ship Graylu, Lyvia and Nali), I think most inviduals ship Nalu and Gruvia because they are the couples Hiro seems to support. I think PhoenixFirestorm gave great reasons why people support these couples. I also think the anime has changed some people shipping habits (since they add a few moments for some couples like Graylu) where the manga doesn't have these moments as often.

Okay, thank you. :) I was just curious why everyone ships those two couples. I wasn't trying to bash any ships. ^_^

It didn't seem like you were trying to bash any ships to me, and I also don't ship the semi-canon ships so I know it can feel lonely sometimes due to it hard finding individuals who ship the same way as you.