Thor: Love And Thunder - 9 Things From The Comic You Need To Know
6. ...And Has To Figure Out WHY He's Unworthy
So, by now you've probably gathered that Jane becoming Thor coincided with a rather unfortunate period for the Odinson. He'd lost his favourite weapon, his father, Odin, was going a bit mental (as in, 'let's rule Asgard like a tyrant!', mental); and to make matters all the more worse his left arm gets sliced off by Malekith. It gets replaced by a cool, shiny, uru-laden one, but you can understand why he wasn't all too happy and losing a limb.
As was stated previously, it takes some getting used to for the God of Thunder to realise he's unworthy. He goes through all the stages of grief, only accepting his new fate in the pages of his own spin-off series, the Unworthy Thor, which saw him faced with the dilemma of wielding the Ultimate Universe's version of Mjolnir.
But whereas the old Thor would've jumped at the chance to find a replacement, he realised it wasn't his destiny. He then continues to aid Jane's Thor as she deals with the escalating War of the Realms engulfing Marvel's various worlds, finding worth in a life without Mjolnir, and a shiny golden arm.