I suppose it really comes down to how one defines "peacefully".
Some might take it to mean you walk away as "friends" and others may simply mean no one was beaten up or killed.
Just because there's no physical attack doesn't guarantee peace. There may be slanderous postings placed on Facebook pages, Instagram and Twitter. Some may even include nude photos that were exchanged. Who knows how someone will take a breakup.
Awhile back I wrote a hub titled "A Breakup Method" and essentially it comes down to (knowing) your future ex and how they react to bad news. If you're breaking up with someone you need to think it all the way through to make sure you want to call it quits for good. I say, think, plan, and execute.
Breakups are always done at the comfort level of the one ending the relationship. The person being dumped has no say on how, why, or when. However this also means the person doing the dumping has no say on how their future ex is going to (react) to being dumped! They have the final say if it will end "peacefully".
Yes you could breakup over the phone, via email, by text, or simply vanish. There is no (new) way of breaking up which has never been done before. Ideally it would be nice to do it face to face but it really does come down to how (safe you feel) doing it that way.