I would like to state some facts and then I would like to make a question to those Juvia/Gruvia haters.
Firstly let me state the facts.
-Gray was worried about Juvia during Tenrou Arc he even got to the point of saving her against Ultear. And let's say this isn't a strong point (it's just the beginning, so I'll agree with you on this one)
-Gray fought with Juvia in the Grand Magic Games and he unconsciously let her hold his hand after the win until he realized what was going onย ย and his tsundere side showed up again.
-Gray fought alongside Juvia during the dragon attack and he even got in front of her to SAVE her! Lyon was with them too and he had stated that he loved Juvia but h e DIDN"t get in front of her to save her.
-Gray said during the beginning of the Tartaros Arc that Juvia shouldn't worry and he would be with her. (if you truly want to see some evidence I will check the chapters and find it for you, but I am sure you know what I mean) He didn't say "We are with you". He said "I AM WITH YOU" while holding her hand and riding this cheetah or whatever it was. Pretty friendly huh?
-During the battle with Silver Juvia was the last person that appeared in Gray's thoughts as he thought that he would die. Do you think it is coincidence huh?
-Silver asked Juvia if she was Gray's woman and he gave her the task of taking care of Gray. NOT Natsu, NOT Lucy, NOT Erza, not any other of the guild.
-Gray said that he would give a straight answer to Juvia after the war, why would he bother to tell her that if he just wanted to reject her? (As you said, Juvia was "rejected" so many time, so why care now? )
-And of course chapter 498 and more importantly chapter 499. Do you think that if it happened to be Natsu in the chains they would kill themselves? Juvia and Gray committed suicide SIMULTANEOUSLY at the thought of hurting more the one they cared about. Gray and Juvia fought so hard and they tried but they couldn't find any other way than to die in order to save the other. Juvia and Gray were put in the chains on purpose because only Juvia's loss could push Gray over the edge. And we saw his state of mind in the last panel. He was devastated, he was helpless. He wanted to avenge Juvia's death and he wanted blood.
So answer me this question. Which person without even a hint of romantic feelings will react like that towards Juvia?
(And before you distort my words, yes I know that Fairy Tail is a family and everyone loves everyone, but I didn't see Panther Lily saving Levy instead of Gajeel, Happy or anyone else go after Lucy instead of Natsu, as I didn't see anyone making the ultimate sacrifice for Juvia like Gray did. Even Jellal saved Erza after he changed to the good side. So don't start your bs on Gruvia. It's one thing to not like the shipping and another thing to say absurd things just so you can promote your hate. It's just ridiculous. Thank you very much.)