I'm struggling to understand - you are struggling to charge the fee because it was convenient for you that the client cancelled? Even though she understands and is even willing to pay the fee?

Sometimes I've felt guilty charging my last minute cancellation fee specifically when I was relieved to not have a session. I'd feel guilty getting paid to have free time. Honestly I think for me it's easier to charge the fee when I feel frustrated or resentful about the cancellation. But at the end of the day, we must value our own time and our own business first. You have set aside the time for the client in advance and perhaps even lost opportunities to see other folks during that time slot. I see the cancellation fee as like a boundary. We teach clients how to treat us and our time. In the past when I waived my fee more often, I actually ended up having a lot more last minute cancellations. Being more consistent about the agreed-upon fee has also resulted in clients respecting those boundaries and my time more. The fee holds clients accountable to their own therapy too.

The intersections of capitalism with therapy are really messy and complicated. But I don't think we should self-sacrifice our own financial well-being out of guilt if we can help it.