The problem is that Ethan built up Justin's expectations so high with promises he knew were unattainable to begin with and just went with it. Sure, maybe he even thought it would work out in the end, but once he'd gotten that gig, he encountered his very first "groupie/admirer" and the temptation was just too strong to turn down. I do believe, though, Ethan was trying not to take up that offer to perform knowing he probably would be open to any fan interaction.
Justin was such a romantic, he truly wanted Ethan to do what felt right for him, and subsequently, it cost them their relationship. Because he couldn't keep Ethan from doing what he loved just to make him thoroughly happy... if that makes sense.
