Why would a guy (bf) do this?

Does not answer calls or texts, and does not give any reason for the sudden disappearance. I'm assuming he wants to end the relationship, and that's the impression his silence is giving me (I texted him the same). Why would guys not even want to give a reason? Btw I know myself and I'm sure he knows too I'm a pretty reasonable person. I would prefer to talk it out rather than a disrespectful way to end a relationship.