God not only inserts people into our lives in order to bless us, but he also causes them to remain with us, for our joy. Paul thought about Epaphroditus in such terms.
In fact he became so ill that he nearly died. But God showed mercy to him—and not to him only, but also to me—so that I would not have grief on top of grief.
Instead of questioning why God takes people from us — a question that we have no way of finding an answer to — let us give thanks to God for his mercy which keeps beloved people in our lives who help us and cooperate with us in the gospel.