Nothing suggested both these characters were bisexual, and cramming that revelation in a big ellipsis feels awkward. I see Taichi marrying Touma as fan service that goes slightly against the themes of the manga: everyone's different in their own ways and it's all fine, sometimes it doesn't end well for some of us because the person we like literally can't return our feelings, that's life, sadly. Making them end up together feels forced because we don't see the relationship developping that way. But people want it, time skip it away, and bam! "they end up together btw, somehow"
But mostly I don't understand the author's motivations for Masumi. She was struggling with having feelings for other women, make her end up with a woman! That feels the most natural way to end the story for her. If Touma can end up happy with a man, why not make Masumi happy with a woman? Once again, we get development during a huge narrative ellipsis, which feels weird and kind of undercuts her arc a little.
It's nice and all, everyone ends up happy but i'm not entirely convinced.