"He got up and went away."
Translation:Li leviĝis kaj iris for.
You can see that this "weird" wording is Zamenhof (L.L. and Lidja) and Kabe sanctioned, so, should be enough for any of us.
Then, I wonder what should be strange about it.
If you're an English speaker, it is a perfect calque.
If you're not, well, it is simply Esperanto being Esperanto.
Li ne simple iris (went), li iris for, (went away). An adverb modifying a verb, nothing original really in any language.
I don't see what kind of ending should be missing.
You're free to use the compound "foriri" if it sounds better to you.