During our relationship, there was one guy from her college group who always made me uncomfortable. Whenever I mentioned him, she said I was overthinking and called him "basically a brother."
We broke up for unrelated reasons. Three months later, I saw their photo together on Instagram. They were officially dating.
I know people's feelings can change, and maybe nothing happened while we were together. Still, seeing that photo made every old argument replay in my head. The hardest part of some breakups is not losing the person; it is wondering whether your instincts were right all along.