Agreed, the love aspect can be further down the road. Kind of like forgiveness for something might be further along the road (or not). The "with love" part sounds rather virtuous - I guess it is, but absolutely not required.
I've detached in a few instances, for me it's kind of a process I think. A person should not (in my opinion) let someone else trample on their boundaries or their feelings - period (I have let both happen).
The only way to stop that is to detach, in all that means. I see it as a withdrawing of being in a "unit". You cannot be in a unit with someone you cannot trust (by and large) with your feelings. Well you can and it will make you miserable and perhaps a bit crazy.
Allowing someone to abuse your trust, emotions, boundaries etc is much more insidious, I think, than people give it credit for. It does real damage to the psyche over time. I think detaching is the beginning of the healing process.
As dandylion mentioned, it is just one tool of many that a person needs to protect themselves from harm.
Because that is what that's about, protecting yourself from harm.