Yeah, I have broken someone else's heart before and it sucks because when you break their heart you break your own too. And in my situation it was just a mutual breakup. That's why it was like no bad feelings. It was just like we just weren't meant for each other.
I don't know about the you break your own heart too in the process, but I understand what you're coming from if it's a mutual breakup and you feel that way. But ultimately, I don't think that's all the time. I think that's more rare than you think.
I'm a human being, of course I've broken someone's heart. The only one I don't regret was my abusive ex when I left them. Yeah, I'm cool with their heart being broken. That's the least I could do for them.