My first adult friend abruptly ended our friendship. I was devastated, and now I'm even more closed off.

• I struggled to make friends with other adults when I became a mother.
• I met a woman at a workout class, and we became close, so I opened up to her.
• She decided to end our friendship, and I'm struggling to let anyone else in.

I moved to a small Florida town after growing up in Miami and have been here for over 10 years. I still find it difficult to make friends in the area — whether it's because of cultural differences or just because it's more difficult to connect to others as an adult.

But a few years ago, I met another mom after a workout class. She approached me and initiated a conversation. We immediately found that we had a lot in common. We were the same age and each had a child the same age.

I was initially skeptical of her motives. As an adult, I had never become friendly with other people my age outside work. I hadn't realized until then how much I had shut myself off from the possibility of making new friends.

Since my son was about 3 at the time, and I hadn't successfully made any other mom friends even though I had tried and wanted to when he was younger, it felt like I should let myself open up to her. I had to allow myself to trust that she was simply interested in becoming friends. When I put myself in her position, I thought it was brave of her to approach me without knowing how I would react. I admired her for that.

She became the first adult friend I ever made, but it wasn't a happy ending.

I opened up to my new friend

We became friends quickly. She wasn't shy about calling me just to talk or inviting my son and me over for visits. She was so candid that it made me feel like I could be the same as her. Soon, we weren't just acquaintances but friends who were more like family.

After living away from home for so many years, I had forgotten how nice it was to have a friend like her nearby. She listened to me when I opened up — something I rarely do.

Since all of my best friends live three hours away, I became increasingly grateful to have her in my life and so close by. I don't think long-distance friends are less true friends than the ones you can see every day, but it's definitely different. In times of need, we could literally be there for each other right away.

She wanted to end our friendship

One day, with what felt like no warning, she told me that she didn't want to talk anymore. I could tell by her tone that she had given this decision a lot of thought. She didn't give me a clear reason. Out of respect for her and maybe my own pride, I didn't try to talk her out of it. I said OK, accepting that she no longer wanted to be friends.

I was devastated.

I had endured painful friendship breakups when I was younger, but I had never been through one as an adult. Beyond college friendships and romantic relationships, I had never opened myself up to anyone as much as I had with her.

The end of our friendship felt different from the end of one with a significant other because I viewed dating with the realism that it may not last forever. When it came to friendship, I saw it as something more enduring.

I'm even more closed off than I was before

I don't regret allowing myself to be vulnerable with her. I'm glad we each opened ourselves up to each other. When I look back at everything that was going on in my life at the time, I am so thankful to have had a friend like her to count on.

But since I was already so closed off to the possibility of making any more true friends past my college years when I met her, the way our friendship ended was traumatic for me.

Since then, I have found myself talking to new people less and being much more closed off in social situations. While it's been almost five years since we stopped talking, I still miss her. I'm glad I was able to experience an adult friendship to the degree of closeness that we shared. But the way it ended has made it even more difficult for me to believe in making any more new friends as an adult.

These days, I'm working on not closing myself off completely.