I was very moody as a young person. I grew out of it/ learned to control it with better nutrition and sleep habits, but that wisdom didn’t come till I was past 40.
My husband and my boyfriend before him dealt with my moods by joking a lot or, if they hit on something like a food or suggestion of where to go that would jolly me out of a mood, they’d use the same strategy over and over. When I was first dating my husband, I would always feel better going to the National Air and Space Museum (which was free), smelling the airplane dope, looking at a few exhibits and then sitting in the cafeteria which had an amazing view in those days (it doesn’t now, they built another museum next door in the decades since) eating something like a hot dog and lemonade. We went to the National Air and Space Museum probably 2 dozen times. We had a few more go-to places like that.
When I got older I had my own moody little friends to deal with and I would try to take them someplace to cheer them up, make jokes or give them pep talks on Instant Messenger, or buy them little presents. This went on for a few years. Unfortunately, since I am not as patient as my husband and was not hoping to marry any of these people, I eventually got sick of them and after one tantrum too many from each of them I told them to go blow and never looked back.
Nowadays I avoid moody people.