What have you learned from past relationships?
All my learning is from relationships - my relationship with myself, the Universe, my family and friends, my romantic partners, and my colleagues.
Even just from my romantic relationships, to which I assume you most meant to refer, I have learned more than can be put forth in 1k characters.
Among the things I’ve learned are these: all things must be learned some time, if they are to be known; patience can be difficult, but it is far more rewarding than urgency; it’s worth testing my intuition; kindness bears sweet fruit, and its opposite is rotten, no matter how tempting; honesty really is the best policy; if I am to learn, I must inquire; if I want something to grow, I must appreciate it; all things require maintenance, even the deepest love; simple and unmediated pleasures are more fun and weave closer bonds than highly stimulating media consumption; it really is a good idea always to say hello and goodbye; ceremonies celebrate and feed pre-existing relationships; …