If the MC is discarded as trash, but instantly gets over their depression by having a new-found 'waifu', then we can safely call this what it is: garbo.
Just like the 'i only have cooking skills->instantly dismantle lvl 500 monsters' manga, or the 'i'm a neet who committed not-alive and was summoned with the bullies, but instead of taking revenge because I'm literally stronger than anybody, I just fuck around with the demon princess'.
We already know that the MC is OP, so there's not really much in the "growth department", but instead of enjoying a power-fantasy or a revenge-fantasy, they introduce unnecessary characters for the sake of ""plot"".
The folks who buy this trash in Japan are better off buying a bowl of udon instead.