wow if that suicide theory was true that'd be real heavy stuff to swallow, but i think it's the most rational way with how Yui's real personality is
but probably that, again, is too dark and the serialization was changing Yui and Yuuta overtime (probably) to suit the happy ending route, idk
can't say for sure if the webcomic ending is better since i can't read the whole webcomic but still, both are good endings for how it is