There could be ton of reasons to break up with someone you love/or even somebody who might be the best person out there. Long list of reasons. Doesn’t even have to be anything bad about other person.

Long distance (work obligations and family situations like kids or elderly parents doesn’t allow much opportunity for seeing each other, visitation time with kids doesn’t match)

Neither person can move to be with the other (custody arrangements for example do not allow for a move at all)

Current life situation simply doesn’t allow time for a relationship at the moment as other things take priority (young kids, elderly parents who require 24/7 care, working full time and attending graduate school full time while being a care giver to dying parent and young children)

The person is great and you love them deerly but they have an addiction that they have hard time beating and you plan on having kids, obviously won’t with an addict

I can keep going. None of those situations might apply to OP but I am just saying just because you love someone it doesn’t mean you need to stay together