Option Explicit

Sub Test()
  
  Dim rngCities As Excel.Range
  Dim vntCities() As Variant
  Dim i As Long
  Dim j As Long
  Dim k As Long
  
  With Worksheets("DatenEingabe")
    Set rngCities = .Cells(.Rows.Count, "A").End(xlUp)
    Set rngCities = .Range(.Range("A1"), rngCities)
  End With
  
  ReDim vntCities(1 To WorksheetFunction.Combin(rngCities.Cells.Count, 2), 1 To 2)
  
  For i = 1 To rngCities.Cells.Count
    For j = i + 1 To rngCities.Cells.Count
      k = k + 1
      vntCities(k, 1) = rngCities.Cells(i).Text
      vntCities(k, 2) = rngCities.Cells(j).Text
    Next
  Next
  
  With Worksheets("Entfernungen")
    Set rngCities = .Range("A1").Resize(UBound(vntCities), UBound(vntCities, 2))
    rngCities.Value = vntCities
  End With
  
End Sub

..so in diese Richtung gehts.