This is going to be rough, because I'm hurrying out to work and don't have time to write a proper response--
He's gone through crap in the comics and other movies, too. Doesn't mean he needs to be reduced to a monotonous, po-faced bore... He's supposed to be Superman, after all.
All this has been done successfully before, while keeping his spirit well-and-truly in tact. He's gone through a lot of stuff.
Also, again-- Why does relability automatically have to turn him into what he was in BvS? There's a wider spectrum of emotion than that. Superman's not meant to be EVERYBODY-- He's SUPERMAN. Put him through the crap he goes through in BvS, he should react as Superman would (yes, he's allowed to be sad and even annoyed now and then). I watch the movie/read the books to see what HE'S going to do, now what you/me/joe schmoe would react. This Superman is out-of-character (admitted by both Snyder and Cavill, due to some idiotic notion that he needs to evolve into the real Superman... over the course of three long movies)... And the one they've got in his place is one dimensional and boring.
Look at the first two Reeve movies. He was damn near all powerful, he was a friendly, smiley guy... He still went through an emotional journey in them. You can have it both ways. The audiences ate them up.
Same with many of the more iconic books-- aka For All Seasons, All-Star Superman.