1. Personal issues or stress: He may be facing personal troubles, work pressure, family problems, or other life challenges that cause him to be emotionally low or unable to care for others, including you.
2. Emotional changes: His feelings towards you may be changing, either because he has lost novelty towards you or because he has new thoughts about your relationship, including whether he wants to continue to deepen it.
3. Poor communication or misunderstanding: Sometimes, the coldness between both parties may be caused by insufficient communication or misunderstanding. He may not have directly expressed his feelings or needs, and you may not have noticed the reasons behind his changes. In this situation, open and honest communication is the key to solving the problem.