Well, I kinda wondered why he had lube in his backpack in the exact moment I read it.
But, I think that I could see this coming. Actually I like your fanfiction because someway you managed to make me understand how they think. Donghae is always so passionate, and in love (sometimes in love with the idea of love) and proud of his feelings...he just couldn't bring himself to have sex with someone else. And, I think, he made up his mind thinking that everybody should love in the exact sane way as he loves.
On the other hand, Hyukjae went through a lot: he had to fight with Leeteuk, fight with his family, fight with himself. He threw away years and years of beliefs just for Donghae. And clearly he doesn't manage the stress and love the way Donghae does. Probably he just needs to distance himself a bit, and prove himself that Donghae isn't his everything. I'm quite happy he found someone else: he'll have the chance to clear what there's in his mind and soul. And maybe, he'll go back to Donghae when everything will be settled.

So, really, does it matter if he had lube in his backpack? XD
Wonderful chapter, by the way.