This was several years ago, back in high school junior year. My first ever relationship, which stretched for seven months (probably far too long), had recently ended, and I wasn't taking it as well as I'd have liked. I had a hard time facing and spending time with my ex, and pretty much went into radio silence with both her and our group of mutual friends. One such friend had known me since sixth grade, and to this day I still don't blame him for how things ended up happening and still call him one of my best friends.

So basically, this friend, I'll call him Jay, and I ended up sharing a class together... I think it was Chemistry? Well, somewhere along the line, my ex, who I'll call Dee, ended up dating him. He actually told me he'd had feelings for her since middle school, when I'd hardly known her at all (we met in Sophomore year). Due to her schedule of taking college classes and high school classes, she'd have several "Filler" periods at school where she was free to go anywhere she pleased within the school. 

She chose to visit Jay, and would often sit with him, talk to him, simple things like that. They were obviously never physically intimate in class, no kissing or even really holding hands, but her presence there always just... bothered me. To put it to words, I guess it felt like hammering in the fact that I had failed to keep her interest, the fact that I hadn't made enough of an effort to spend more time with her. I think I was comparing how our relationship had been with her current relationship with Jay. We were... lukewarm, only saw each other for sparse dates, often without very good conversation, and exactly zero physical intimacy. Yet here they were, able to make time and talk to each other fluidly and easily. I'd even seen them in the common area once when they both had a free period, just talking and holding each other.

So after a while of this, I decided to take things into my own hands. After class I pulled the teacher aside and asked him to keep Dee from visiting the class again. I didn't want him to tell her that I was the one who requested it, but I feel like she knew anyways. Thinking about it now I feel so petty about having done that, like I should have just let it roll over my shoulders. I let my jealousy and low self-esteem get in the way of her happiness.

I don't know how aware she was about how I felt about her and Jay's relationship, and I never outwardly told her. I sort of made up and broke radio silence near the end of senior year, but it was never the same, and I haven't spoken with her once since graduation. She and Jay ended up splitting up, and I have spoken to Jay since, even visited him when I was back home.