
A. They bonded probably around 13 years old since heats usually coincide with entering puberty. Their current ages are probably between 19-21 seeing as Iriya is older than 18 and just now having his first official heat.
B. They aren't intoxicated/drunk. Iriya is in heat and Uryuu ((idek his first name since it hasn't been revealed yet in the spin-off and I'm behind on the main story)) is being affected by Iriya's pheromones.
C. They've already bonded so even if Iriya's collar came off he wouldn't be able to be bonded to anyone else. Most of the time omegas aren't even supposed to stand the touch of another alpha or their pheromones once bonded.
Hope this helps.

but his father said at the end of ch 1 that since they wernt adults that he bite did nothing so they havent bonded yet.... thyere fated pairs tho ig iriya is repolsed by other alphas since he came in contact withhis fated alpha not because they bonded well not yet...and i mean intoxication by their phermons theyre both arnt in control litrally the ml is just as bad as the other alpha then for not controling his self and succumbing to his instinct

The bonding must have been clarified in the re-upload of the prolog 'cause in the initial one it never specified. I usually ignore duplicate upload chapters 'cause most of the time it's just this site's bot nabbing shit without permission.
But then again, if they hadn't bonded that first time then why did Iriya not go into heat all those years well after the period in which omegas have their first one? His heat wasn't triggered till he was in the same room as the alpha he was bit by. Either way, Iriya still didn't react positively to other alphas the entire time he was separated from the childhood one.
On another note, is this your first omegaverse series? It's a very common occurrence that omegas and alphas succumb to their instincts. It's how a majority of these series start off. It's not like they are completely without will or reason, either. Iriya resisted the other alpha but gave in to Uryuu because they are fated. It's harder to resist the pheromones of someone your soul has literally chosen to be with till you die. Yeah, sometimes the characters find it hard to come to terms with how it happens, but it's not like they are date raping each other.
first they look young how old are they specially the alpha,second agh again with the intoxicated SA again, hepled him to just fuck him, thank god his collar was unremovable, this author's art rlly be saving them lol