Mating conflicts happen when you create in-context sketch relations and then create distance mates using the components and entities that use the sketch relations.
The conflict happens because the distance mate tries to pull the faces apart, while the in-context sketch relations try to pull the faces together. These mate conflicts cause problems such as slower rebuilds, "growing" parts, "walking" origins, and incorrect drawing views.
Such conflicts happen only if the mate conflicts with an existing in-context relation. You can create parts in the context of an assembly without referencing other geometry. These types of parts do not cause a conflict if you delete the inplace mate.
Example