Ultimately, when someone ends a relationship, it’s because they don’t care enough to want to keep the relationship going.
The detail might be different but that is what underpins it. If someone ends a relationship because of other demands on their time or other commitments or hurdles such as distance, it’s because they don’t care enough to make the effort that would keep things going despite those hurdles.
And “feeling it” is not something you can manufacture. There have fabulous men in my life who ticked lots of boxes and with whom I really wished at the time I could have felt it but I just didn’t and I know men have similarly just not felt it with me or have just stopped feeling it. It can’t be forced. And as PP have said, it’s probably got nothing to do with anything your DD is or isn’t or did or didn’t do.
And that is completely fair enough but it’s very hard to be on the receiving end, particularly after 3 years which is a meaningful period. Given that time period, I’m even more inclined to think that someone else has caught his interest.
It’s horrible for your daughter now. Most of us have been where she is and we know that time and getting very busy helps and that she will feel better but it will probably be a good few months or more before this stops dominating her thoughts and feelings.
Ultimately, learning that you can have your heart broken and feel happy again and love again is actually very empowering but obviously she’s not there yet.