Those are not different bodies (notice you only have 1 Part, 1 Body in the tree). These lines are showing changes in the tangency or something similar. You should might be able to combine these three faces into one by using the Tools (from the pull-down menu) -> Merge -> Faces.
If you are annoyed by these line due to the mesher resolving these lines, you could try Virtual Topology in the Meshing application.Â
You are navigating away from the AIS Discovery experience