welp i for one as a mika fan, hate how he's been tagging along whatever yuu desires without being able to decide on his fate, the character feels hostage and it has hurt his writing. Back before, he was the voice of reason for Yuu and now he'll just accept anything and "behave way more freely" (not rlly lol he's still hostage of yuu's shenanigans) since he's not angel mikaela, but i think that specially since he's not him, he should help yuu and not just tag along a dead end plan. He tries to convince Yuu, yet he won't oppose? He's his demon ffs, he can literally possess him to forbid him doing anything stupid. Just as Ashera said back then, Mikaela wants to die not because he doesn't belittle his life, but bc his time is already gone! Where's mika's reasoning from back then? Obviously Yuu isn't following Shikama's plan entirely, but not bc he won't do the same, actually, he's following Shikama's plan but on steroids, his steps are leading into the same consequences! How could Mika ever think that's okay! Even if he sees Yuu's desires, even if he sees his obsession, you just can't let someone precious to you throw himself away and tag along with him.....
Hmmm... I have an answer but it'll be extremely long. Sooo, give me a bit of time anon. Because surprisingly, there's a real explanation to this. 😅
P.S: My bestie liked your insight (she loves Mika so much at at first, long ago, she had this kind of questioning until her insight changed due to her master degree)