People who have lost their loved ones or experienced separation may become dependent on others for happiness. It is not necessary to seek happiness from external sources such as people, habits, or materialistic things, etc.
One thing I strongly believe is that you can never replace a person with another person, thing, or anything else. Accepting that someone is gone and can no longer be replaced is important. Otherwise we deceive ourselves by replacing endlessly.
People often fall into the trap of depending on someone else for their happiness. They create an image of that person based on their own imagination and assumptions. When their illusions get to fade, they feel that the person has changed. But the person was always the same and it is our understanding that changed. Earlier, we justified their actions because of our attachment and imagination. Once those justifications fade, reality becomes visible. We never truly see a person completely, we fill the gaps with our own imagination.
It is true that people need something to hold onto to feel grounded and stable. It can come from spirituality, philosophy, or deeper understanding of life but not from depending on another human being or materialistic addiction.
Dependence is suffering and the Freedom begins when we finally realize that happiness was never outside.