People value my work, my time, and my love.

Of the three, time is the one treated as free. Work has a rate. Love has a name for what happens when it gets abused. Time just leaks quietly into other people's arrangements: the meeting that could have been a message, the favour that assumed a whole Saturday.

Your brother-in-law isn't being malicious when he assumes the whole Saturday. A thing offered without a price attached gets taken at that price.

Attaching one isn't hostility. Saying you can do an hour rather than the afternoon is information, and most simply update. The ones who don't were never valuing it anyway, which is useful to find out early.