Loosing faces while deleting a loop - some times leaving behind vertices.

[ForrestGimp]

All Quad based geometry.
when the geometry become complex, some times I need to insert a loop but not in the middle lets say in quarter, so I don't use offset loop because that is an other issue, so I insert a loop in the middle and then I insert an other loop in the middle of the half, so I'll have the second loop perfectly in the quarter, but when I remove the first loop I loose faces and some times it leaves behind vertices, it happened to me a million time, and it is frustrating.
you need a complex model to reproduce it (you can use the AUDI TT model)
please see the video.
QFT Loosing Faces-Del Loop.zip