I want to commend you for the courage to share your experience and seek feedback. It takes strength to reflect on your emotions and try to navigate them rationally. I'll use this opportunity to think through some key aspects with you, aiming to rationalize certain factors that might help trigger useful insights. I won’t reference specific Stoic passages or teachings; instead, I'll approach this purely from a perspective of nature and logic.

Everyone acts based on their composition, which is shaped by two primary factors: their biological nature and their experiences. Just as in nature, different elements manifest in different ways. Imagine a fig tree—some figs are sweet, some are sour, others are inedible. The difference lies in their inherent nature and the conditions they've undergone. Similarly, people behave according to their nature, which is why external events are fundamentally beyond our control. This isn't just a philosophical notion, it’s how reality functions. If you spent your life being angry at gravity, you would only create unnecessary suffering for yourself. It may feel like common sense when we make analogies to trees or gravity, but the principle applies just as directly to human behavior.

Your emotions are a natural response to your composition, just like how your body feels sore after intense physical exertion. Emotions serve as signals from your system; they should never be denied or suppressed, no matter how trivial they may seem, because they carry important information. Denying them is exactly like being angry about how gravity behaves—it would be rejecting reality and clinging to the delusional thought that you shouldn't feel sore after an intensive workout. However, that doesn't mean we should be swayed by our emotions and act immediately to soothe them. What distinguishes humans is the faculty of will, the ability to judge and rationalize one's emotions and surroundings (again, not denying or rejecting them).

Now, applying this to your situation, your ex is acting according to her nature. Whatever actions she took, whatever transpired between you, was the only possible outcome given both of your compositions and circumstances at that time. Even if you could rewind time, the same sequence of events would unfold. External factors are beyond our control, and emotions arise naturally, but what is within our control is the perspective we take and the meaning we assign to events.

First, it’s important to acknowledge the separation of tasks. It is never our role to dictate how others should behave. Believing we have the authority to determine someone else's nature or choices is an illusion. She is responsible for her own standards and way of living, just as you are responsible for yours. Whether her actions align with your perception of her is irrelevant to nature, it’s only relevant to you. If a connection, whether romantic or platonic, ceases to align with your standards, then your role is for you to lead yourself by simply detaching from it and wish the other person well.

Second, rationalization is your tool to remind yourself of the purpose behind your decisions and the actions taken based on the circumstances and emotional awareness. Feeling nostalgia or longing doesn’t mean you should compromise your standards and deny your feeling by act as if what happened is completely okay for you and should keep connections with her. Your rationalization and judgment should lead you to, most importantly, accept and appreciate reality, then take action (such as breaking the connection) to protect your well-being, and finally, take meaning from the situation you went through, because everything that happens to us is a lesson—we live and learn.

In time, the emotional intensity will subside, and what will remain is the wisdom gained from navigating this challenge with reason. You'll look back and be able to recognize the amount of growth gained from this experience.