Short answer to the question in the OP: yes.
When we were in college, M and I dated for two years. We were deeply in love, got along wonderfully, and we were starting to think seriously about marriage.
But, M was planning to go to medical school. She was very serious about her schoolwork, and given the sorts of courses she was taking, she had to spend a lot of time studying.
And, one evening, M told me that she had to break up with me. it wasn’t that she didn’t love me (she did), it wasn’t that she didn’t want to be with me (she did), but she had come to realize that, in order to achieve her goal of becoming a doctor, for the next six to eight years, she needed to focus on nothing but school; she didn’t feel it would be fair to me to expect me to take “second place” to her studies, and she felt that she wouldn’t be able to devote the time and energy she should, to be my wife.
I was, of course, crushed. I understood her reasoning, and it wound up being, as breakups go, about as positive as it could possibly be. M and I remained friends, and once we got past the initial awkwardness (which took maybe six months or so), she and I would socialize (platonically), have lunch together occasionally, etc.
For my part, I started dating the woman who became my wife two years after the breakup, and while I love her deeply, M stayed in the back of my mind for many years – I would wonder to myself about the road not taken: “What if I told her I would wait for her?” “What if we had tried to stay together?” I still loved M (and, truthfully, I still do), but I’d say it probably took at least a decade, maybe more, before those thoughts of regret finally started to fade.
As it turned out, M wasn’t able to go to medical school – some psychological issues developed for her about two years after we had broken up, and those sidetracked her studies for several years. Once she got past those, she realized that medical schools would be unlikely to admit her (due to that history), and she changed course, eventually earning a Ph.D., and becoming a professor.
But, the other thing that developed for her was that, in the years after our breakup, she came to realize that she was bisexual, and preferred women to men.
M and I have always stayed in touch (it’s now 31 years since our breakup), and, three years ago, after same-sex marriage was legalized, she invited me to her wedding. M’s family (whom I hadn’t seen since 1987) asked me to sit with them at the service. At the reception, I met several of M’s former girlfriends, from many years after she and I had broken up – all of them knew of me, and said that M had always spoken of me in very fond terms.
As the reception wound down, M and I got to sit and talk for a few minutes. I told her that I was so thrilled for her, that despite the issues she’d run into after we had broken up, that she’d done some amazing things with her life, and that she’d found someone wonderful with whom she was sharing her life. She and I both acknowledged that we were, in a way, still in love with each other (and likely always would be), and that, while we both knew that that love would never again manifest in a romantic relationship, we still cared deeply for one another. I don’t think I could ever ask for a better ex.