I always broke up in person. Most of the time they weren’t long-term relationships, and a simple “I don’t want to see you anymore” was sufficient.
Once I made the mistake of telling a guy (in high school) that he was too nice. What I really meant was “you have no spine” but couldn’t bring myself to say that. Later he told me that his parents suspected I was gay because I had so many girl friends. I guess if I had a lot of guy friends they would have called me a slut.
The only long-term boyfriend I dumped was also dumped in person. That was tricky because I was 6 hours away at school when I decided to end the relationship. We had been together for almost two years, and I felt he deserved better than a phone call. He knew something was up, and drove down to see me one weekend as a surprise. When he called from a hotel that Saturday morning, I was sleeping in a friend’s room down the hall. A guy friend. My roommate came running to pound on the door, yelling that my boyfriend was on his way over. The guy was just a friend, and I really only slept there. Still, not the kind of thing a boyfriend would be happy about. Anyway, when my boyfriend got to our dorm building, I waited until my roommates left for breakfast and just told him I wanted to break up. I was honest, but not mean or dramatic. He was a very nice guy, but just not right for me. He was very upset and left right away. I cried a little just out of relief, and spent the next few weeks trying to get him to understand that I would not change my mind.
Breaking up any other way is cowardly, IMO, unless the person you’re breaking up with has shown signs that they may become physically aggressive and you have reason to fear a confrontation.