as someone who's had experience dealing with idols and their fans...dating is still a rather grey area to me. sometimes i think i understand why companies are so controlling of their clients, but at the same time, they're really restricting and caging them. they're protecting their well-being from a certain group of fans (trust me...i've read some horrible stories!), but then again their using their "pure" image for profit. it's definitely a strange aspect to the industry.
honestly, i think it's different for everyone. it sort of depends on a person's relationship with their company. Tomoya Nagase began dating ayu when he was young and it was a private and long term relationship too. i don't think Johnny's made a big fuss over it because perhaps Nagase did everything right with the company. it contrasts so differently with other Johnny's, like Jin Akanishi. i'm pretty sure he is black-listed now and his whole career stopped overnight. he had a different situation tho with knocking-up Meisa Kuroki, so.....
i definitely think ayu has control of her love life. someone who had a boyfriend (a Johnny even!) during the ultimate prime of their career and not let it affect their work is sort of an anomaly. she is definitely not as big as she used to be, but i think because she's well,
ayumi hamasaki, people are still invested in who's she's dating and they will talk and gossip. but ultimately...she's had it easier than others, IMHO.