I'm a fan of them! In an otome game, I don't necessarily need every route to end with the protagonist and her love interest living happily ever after. If the ending makes sense for the characters and feels meaningful to their relationship, I'm totally fine with it being a little messed up or bittersweet.
I love merry bad ends too! They tend to stick with me more than straightforward happy endings. There are plenty of things that make me go "hmm" in real life, but that I end up loving when they happen in fiction. There's just something about twisted relationships and situations that really gets to me.
Sometimes I love a merry bad ending, especially if it's written really well and not out of character at all.
I probably prefer happy endings more, but if they're too predictable or generic, a merry bad ending always succeeds in making me thrilled. Any twisted ending is always welcome lol!