I think my first anwer was too ambiguous so I will explain a little bit…
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He actually didn’t went back in time, they’re in another dimension completely. Do you perhaps remember the silver thing Irene was holding in her hand before being attacked by that monster and ended up dead? Ml got a similar piece, and that artifact have the ability to “start again” akas send him to another dimension that Irene were alive (ml wanted to see Irene again), but the tricky part is that for that goal, he needed to kill all the monsters in the world (not dungeon left), he did it one time, then a second, a third, and a four and more than a thousand times but Irene presence was still missing in everyone of them, she didn’t exist till this “second life” that we are seeing. That was actually what make him like that, he did have his holy power to purified himself, but they weren’t able to work at the same phase he was killing and entering dungeons ( + he did that so many times alone and without a purifier ) so he ended up corrupted . The Michael we are seeing rn, is not human anymore, but he’s still the same Michael from the first live, just a bit much more crazy….
We have a really long way too see all this and his redemption arc, but Irene was his biggest regret…the ring she’s using to level up ranks, is a ring that Michael got for her even at the cost of his both eyes, he’s a good ml, just have a little of patience.
In a simple anwer, yes, he loved her and was even planning to asked her to marry him (The same day that he ended up seeing her cold body in the dungeon ( ̄∇ ̄") ).
His redemption arc is good, very heartbreaking. Irene was and is still the only existence that he truly desired and loved, he was horrible at communication though in his first life bc he was a paladin and the high position he himself represented to everyone.
If u have more questions, just ask, I read the novel recently so most of it is still fresh in my mind ╮( ̄▽ ̄)╭

Im sure he bring back the time!