I discovered four lessons I learned from the most outstanding teachers I’ve had in life, my ex-girlfriends.

I am sitting across a restaurant table catching up with the one ex-girlfriend that I thought I would be with forever. Of course, I was 27 then, and I thought I’d be young and have a tight butt forever too. As we laugh and chat about our lives, I realize that my ex-girlfriends have been my most prominent teachers in life.

Later, searching for more understanding about past relationships, I sprawl out on the floor with a glass of wine and old journals. As I read my own words and remember the sweet beginnings, the vulnerable miscommunications, and each ultimate demise, I realize two things at once: that I never really knew what I was doing and that anything I do know today is because of the women I now call my exes.

Here are the top 4 things I learned from my ex-girlfriends.

1. Relationships were a mirror of how I felt about myself.

For years I blamed my bad relationships on my exes, and then I got into the worst relationship I’ve ever been in. Our communication was toxic. One moment she adored me; the next, she was emotionally abusive. When the relationship ended, I had to look at how and why I participated in it, to begin with. I realized that when we started dating, I was in the middle of a depression that left me feeling hopeless and wondering, “Who would want to date this?” Looking back, I recognized that I wasn’t dialled into compatibility or red flags in that checked-out, self-despising state. Our relationship was just a reflection of how I felt about myself.

2. Love doesn’t trump incompatibility.

In the movies, when things go awry with our leading couple, there is a moment when one lover realizes that their love can overcome any challenge. Love, the message tells us, conquers all—uplifting cue music as our lovers race through an airport toward each other. In real life, I have never seen a single person racing toward another in an airport. When I got into a relationship with a fantastic woman with every quality I valued, I was confused because we couldn’t understand each other. I began to appreciate that, to put it in Seinfeld’s terms, we were great on paper. As the relationship progressed and we rarely met in the middle, I began to understand relationships differently: it’s not really about blame. I realized nothing was wrong with her or me; we just don’t fit.

3. I had my guard up in most relationships. 

When life has gone sideways, I often feel alone in dealing with it. I could never understand why, periodically, I felt supported and safe, while other times, I felt like I was dangling out on a tree limb by myself. Then I had a medical situation that left me completely vulnerable and without any walls. And to my surprise, I felt supported. Finally, I connected that the times I felt support was when I let my guard down, I allowed people in enough to see where I was struggling and support me. I didn’t understand for many years that the ability to be vulnerable or not was what separated those times from the out-on-a-tree limb times.

4. Losing myself in relationships was from a lack of boundaries.

Of all the lessons I have learned about love in 20 years of dating and relationships, learning how to set and hold appropriate boundaries has been the biggest game changer. In past relationships, I seemed to get lost, like part of me faded away for the relationship to work. These days, I learned to check in with myself on what I need and to balance taking care of myself with taking care of the relationship. I developed more skills around communicating and worked on taking responsibility for myself. This learning helped me take ownership of my happiness.

Today, I’m working on focusing on gratitude for all the things I learned from past relationships. Most days, I can hold gratitude for my most prominent teachers in life – my ex-girlfriends. Maybe that’s all we can do – take what we’ve learned and move forward with a grateful, open heart.