People feel broken when their partner left when they need them very badly. I think those people left their partners because they become worthless to them and they think that they will find a better partner than the current one or they have options available.
The problem is we value more to our partner’s than us. We have to understand our worth first, we have to put ourselves on top priority. Make yourself complete without anyone else. In that way, you can enjoy your own company and when you start enjoying your own company you will not be dependent and have no expectations of anyone. And that way you can stop others from hurting you. Know your self-worth first. Rest everything will fall into place.