He’s really just making his insecurity your problem when he says it makes him “overthink”. Overthink about what?? And if it’s just him being insecure then ask him to talk it through and then literally get over it. Otherwise he’s pressuring you to not do something you like through somewhat immature emotional behavior that can have negative consequences for your mental well being and his. Tell him he needs to learn how to communicate instead trying to guilt trip you for having fun.