Not sure if thats the best title but im not sure how else to label the current situation. One of my players is a werewolf and was afraid that one of the enemies was going to chase him down to kill him, so, he ran 50 miles out from the town he was in and swam into the middle of the ocean and hid there. He casted water breathing on himself and spent the whole session separated from the party and just running away as far as possible.
I didn't have a plan for this as I didn't think he had water breathing as a spell yet, I would check in with his character periodically to see if he was trying to do anything specific or just wanted to do anything at all. The other two players in my campaign ended up in a fight with the enemy that the werewolf was hiding from (in hindsight I should have postponed this fight a little longer but I really didn't know what else to do) which made him feel left out. I mentioned to him that he found an underwater city ruin while he was in the ocean to try and set something up for his character but he dismissed it because he didn't want to get caught by the enemy.
We stopped the session half way through the fight and he was just very upset that he was being left out of the action, I told him directly that I would have something planned for him next session but I don't think it lifted his spirits. I'm going to make sure he can regroup with his party next session but I'm not really sure how without it feeling random and rushed, and I also don't want to run into this kind of thing again. Any ideas?
(sorry if this is too vague or worded weird , ill clarify anything if needed)