Companion ditched me at the end of act 4 *spoilers for act 4*

[ShadowWarrior496]

So ulfar went walk abouts at the end of the chapter, anyone know if i can get him back? basically i defeated uralon and the the annoying boss afterwards, had dialogue on the planet with several npcs and compeleted the quest 'the siege'. Afterwards tried to leave the planet but ulfar said we had to go find his mates on the planet, couldnt find the area they were in (looked for well over an hour), so just decided to move on and the bam he's no longer with me. Also noticed that baleful howl quest line is now listed as failed, oops.

[reevestone]

You didn't find the area of the map with Ulfar's two companions and the Helbrute boss.

You need to do several things in The Siege related to Ulfar's personal quest to keep Ulfar. As you saw, he demands to accompany you to the planet, if you refuse him he permanently leaves the party. On the planet, you need to find the two other Space Wolves and the Helbrute boss fight and clear that... or else Ulfar permanently leaves the party.