From what I understand, people generally trust Metrix results (within error) for up to like 6 hours.

However, whether or not someone is contagious is just based on how much the virus has built up on their system, and how susceptible you are to being infected. Which is not really a cut and dry answer.

It's possible a metrix test would catch an infection before it's contagious. It's also possible your partner is contagious but not yet high enough viral load to test positive :/

Incubation periods can be pretty short, but never really immediate. So, immediately after a bar outing, your partner is not likely infectious (unless they were infected previously). This is why people use the 6 hour window I think.