Feeling upset or sad when someone you care about leaves is a very human and natural emotion. It does not make you weak at all. It's essential to remember that everyone experiences emotions, and they are not indicative of weakness. They are part of being human.
Having attachments and emotional connections to people is a sign of empathy, love, and vulnerability, which are all essential aspects of healthy relationships. Feeling a sense of loss or sadness when someone you care about departs is entirely normal and doesn't diminish your strength as an individual.
It's crucial to allow yourself to feel and process these emotions, as suppressing them can lead to further distress. Remember that everyone experiences separations or changes in relationships, and it's okay to seek support from friends, family, or even professional counseling to help cope with these emotions. Embracing your emotions and finding healthy ways to deal with them is a sign of strength and self-awareness.