I feel the need to remind people that the nature of relationships varies person to person and the specific paring involved.
What may work well in one relationship may be a terrible thing to do in another.

However, that being said there are usually a few universal things that every relationship benefits from.
Mainly being things like trust & honesty. Without it the relationships days are numbered.
Not to say anything you did warrants any kind of mistrust though, farthest from it.
But Griever and Kestrel have a point in that he probably deserves the honest reason for what's going on.

Especially as a fully grown adult who should have good control over his emotions and decision making.
If in the end you still think it's best to be separate that's fine. But I would suggest giving him the honest reason as to why you broke up with him.

Though it honestly isn't really our place to be giving advice like that or saying "You should do this" to begin with.
So obviously feel free to completely ignore us in this regard.