Do I have to join my friend's standing ovation to show I appreciated the play?

My friend stood as soon as the cast bowed and tugged my sleeve. 'Get up. They worked so hard.' I kept clapping from my seat.

I'd enjoyed parts of the play and admired the performances, but the ending hadn't worked for me. Standing felt like expressing an enthusiasm I didn't have. My friend said I was being stingy with appreciation and that the actors could see the gaps in the audience.

I wasn't trying to deliver a verdict from my chair. I thought ordinary applause was appreciation too. On the way home she called me a critic, and I realised we were judging each other's reaction more closely than the show.

Can I explain the difference without making her feel her wholehearted ovation was less thoughtful than mine?