This guy pivoted hard off a fresh friend zone situation with his crush. That's no easy business, getting all worked up to take the person you like to a concert, and then after inviting them along, you find out that the romantic interests are one-sided. Pretty brutal no matter how you slice and dice it.
That being said, he went ahead and asked Redditors whether or not he was a jerk for offering the concert ticket to someone else. The verdict would seem to be a solid, you are NOT the asshole.