How do I ask about a choir solo without making the chosen singer uncomfortable?

The solo list went up before rehearsal. I'd auditioned for one verse and practised it for two weeks. Another singer's name was beside it. I congratulated her, then spent the rehearsal barely looking up.

Our choir director said everyone's auditions had been useful, but didn't give individual feedback. I want to know what to work on. I also know part of me wants him to say the choice was close.

A friend suggested asking why the other singer got it. That sounds like making her performance the subject of my disappointment, especially because she sits two chairs away from me.

Can I ask for a short conversation about my audition while being honest that I'm disappointed? I'd rather get something useful from preparing the verse than turn every rehearsal into silently comparing our voices.