This could be for a few reasons. Firstly that male culture often doesn't let men feel like they can truly open up to anyone except their romantic partner. So if they lose that person, it feels like they've lost the only person who truly understood them or accepted them for who they are. And if they're broken up with it can be even more painful as they feel the only person who understood them, rejected them, and that hits harder than someone who didn't know you that well, rejecting you.

I think having a wider variety of people in your life that know you well, that you can be vulnerable with and share your true self with - is key to stopping this. The fact women tend to have non-romantic intimate friendships alongside their romantic relationship could explain why women don't tend to kill themselves as often as men do, because they have a stronger social network that looks out for them and supports them, and even if one person leaves, someone else remains.