Summarize the following:
That is their job, not yours. Being in a relationship with someone who sulks can, over time, damage your own self-confidence and wellbeing, making you wonder if you’re to blame. It’s not your fault—your partner is responsible for fixing their own behaviour, not you. Essentially, your partner needs to learn how to soothe and “parent” themselves before they’re able to be in a healthy relationship. It can be hard not to respond in anger or by sulking yourself, but work on staying open to communication. Tell them that coming to you directly and talking about it is perfectly fine—and you’re much more likely to respond in a loving way if they talk about it rather than sulk about it.  If they’re finally able to sit down and talk about the problem, encourage them to tell you what triggered this response and how they felt.  For example, they might say “You were half an hour late to dinner, which made me feel like you didn’t care” or “I saw you laughing and talking to another man, which made me think that you like him instead of me. I was jealous.” This may feel unnatural at first because it’s a very vulnerable and straightforward manner of communication. However, once your significant other starts talking to you this way, you’ll be able to address the problem much more easily. If your significant other is still struggling with this or is becoming more and more controlling, look into getting professional help through counselling. Go through the counselling process can help your partner realize that sulking hurts both themself and the people around them.  Counselors can give you some advanced techniques for dealing with this behaviour as well.  A couples therapist may even see both of you separately to help determine the source of the issue for both partners. The counselor can then help you work through individual issues. If your partner can’t break this pattern of behaviour or if your relationship has become unhealthy, a counselor can also help you evaluate whether or not you should stay together.  To find a good couples therapist, ask your doctor for a recommendation or check online at websites like the American Association for Marriage and Family Therapy or GoodTherapy.org. if you don’t see any changes. If you’ve made it clear that this behaviour is unacceptable and you still don’t see any changes in your lover’s behaviour, it’s probably time to go your separate ways. It is not your responsibility to continually validate their immaturity, jealousy, and insecurity. That isn’t fair to you or healthy for either party.  Because your partner is already prone to bad behaviour like sulking, the process of breaking up may be extra difficult and emotional. For a safe and healthy breakup, be respectful but firm. Tell your partner why you want to break up and set clear boundaries. For example, you could say “I can’t stay in this relationship if you can’t communicate with me when you’re upset. It seems like you have some emotional issues to work through, and I wish you all the best, but we need to go our separate ways.”

Summary:
Remember that your lover needs to learn how to comfort themselves. Encourage them to express why they’re upset in the future. Consider counseling. End the relationship