Why did they not give me a proper reason for breaking up with me?

See either the person had some other priorities.or the person started liking someone else and had no guts to face u and tell the truth.or he might have disliked something about u and wanted to stay away from you for that reason

sometimes things doesn't need to have a main reason. just accept the fact that he wants you to set him/her free.

There are many reasons why people don't explain much. They could just want to avoid more drama. They wouldn't like to hurt you more. Or maybe they don't think they reasons would be enough for you. They could just want to avoid more conflict. They could even be afraid. Or maybe they don't really know how to explain it.

They were probably too nervous to confront you. Obviously some people feel really guilty when they have to break up with somebody, because they don't want to hurt anybody. Its probably because even though they wanted to break up, they still cared about your feelings.

It could be for multiple reasons. It could be that they don't know the exact reason why. They just know it was wrong for them to continue on and didn't want to say that because it doesn't seem like a valid reason why to break up. It could be that they know why, but they still like you and don't want you to question yourself. It could be because they don't like confrontations and are scared to see you hurt. So it's easier for them to avoid the talk. Most of the time, it's them not knowing how to deal with the situation and wanting to avoid it as much as possible.

They probably are confused or don't want to hurt you. Could be also because they don't want to be seen as the "bad guy". Some just don't feel it anymore. Emotions and relationships are sadly complicated..

There are different reasons but i believe a reason could be because they didn't exactly know themselves and felt like they could not give you a good reason.

Sometimes there isn't a "proper" reason. We always want relationships to end definitively, but in reality the reasons for a relationship ending can be very subtle and abstract.