She is the epitome of attention.
All the attention she receives is seemingly unfair. She has unknowingly dolled that simple, straightforward fact for a good amount of time—a cruel, excessive amount of time for him. Dawn, herself, defeated the stunning beauty of a woman notoriously known for being the champion—ex champion now, in one single battle. No usage of any items to assist her in the quick, less than ten minutes of a Pokémon duel surely drew up nothing but awe towards the bluenette. He himself, was also vaguely impressed, shocked as well. Never did he think that she would reach her objective in only a matter of a few, short months.
On top of that, Dawn has also gained popularity for defeating that wretched, nuisance of an organization called Team Galactic. From driving away the grunts during their raid, to rescuing all of Sinnoh from almost being devoured into the timeless, space-less Distortion World, her achievements made her strive even more.
Oh, he feels happy for her, no doubt. Sure, he'd feel a twinge of jealousy here and there when he'd flip through the television, only to have nearly every channel to sport on her face, name, etc. But nonetheless, he was proud of her. Barry simply was not fond of all the awareness she gained. Most of it, for his eyes, was rather unnecessary and irrelevant. Girls looked at her as a role model, which was okay. But the male population was the problem.
They swoon over her, admire her, want to get close to her...
It had come to the point where she barely had time to hang around with him. All the rendezvous points he had managed to make with Dawn, were mostly called of by her, when she had to quickly decline due to her either meeting up with somebody else, or with having to work at the league.
He grew sick of it all. What happened to the good ol' times, when they would spend the whole day together? No interruptions, no peripheral excuses to decline, no nothing. Those were the days that he missed. Barry seemed to dwell on the certainty that those days may never come to be anymore...
All he could do was wait. Wait for the day when she could return for once with nothing to do. Wait for the day when her schedule wasn't clouded with things to do. Wait until she was free from her status as the Sinnoh Champion, and simply be that one, plain trainer from Twinleaf Town.
Luckily for him, he didn't have to wait long for that.