NTA, you do a lot to support her. But you’re looking at these tickets as tickets, to see an artist you both like but aren’t superfans of. She’s most likely looking at them as what they represent — a reward and acknowledgment for all her hard work. And her wanting you to look for the tickets is her wanting to know you appreciate her. So I wouldn’t just brush this off and assume she’ll get over it. Instead maybe sit down with her and say something like, “Look, I know you’ve been working really hard, and I’m so proud of you. And you do deserve a reward, and I really wanted to give you that. But unfortunately I’ve been looking, and I can’t find those tickets for under $900. So is there anything else you’d like that would be a good reward, maybe another show or a nice dinner out or a weekend away?” Or if you do know something she’d like — tickets or jewelry or whatever — surprise her with it and tell her that.