Paying attention to how you feel after hanging out with someone tells you more than how you feel during.

During is a poor measurement, because adrenaline, laughter and wanting to be liked are all mixed into it. The hour afterwards is quieter and more honest: lighter, or flat, or vaguely ashamed of things you said to keep up. That afterglow or that sinking is data about the friendship rather than about the evening, and it is easy to collect.

Check in with yourself on the way home this week, twice, about two different people. One word each is enough. Give it a month before you conclude anything, since any single evening can be off. Then spend more time with whoever keeps leaving you lighter.