Really? I personally relate to Misumi a lot. I think of her sexual orientation a lot like mine-- pansexual with a huge prefrence for females. At the very least she's bi with prefrence to females. This is honestly mostly projection (but thats hows i understand the development of her relationship tbh) It takes a lot of time for me to develop attraction to a male. Its not comphet but just unlikely to happen as much as it happens with females ykwim? But it's not impossible. For the longest time I thought so hard over whether I was a lesbian or pansexual until I fell in love with a man the hardest I've ever fallen for anyone. And it wasn't anything I expected, much like misumi. Then slowly I started realising that the feelings are there. I still like men. It's just that I have a preference for females. That's it. So I just...really loved how Misumi turned out to be. It showed that outside those panels, she had a life and experienced a wide array of things beyond our understanding, which led her to be in relationship with a man. I believe this turnout was a really difficult and ardous result for the mangaka to have made and I can imagine the opposition they must've gotten over this, from editors and fans alike. Realising yourself is a never ending task and you find more things about yourself the more you live. Misumi's first hurdle to realising her sexual orientation was coming to terms with the fact that she could confide to people important to her. And crossing that hurdle allowed her to gauge her feelings in a more undiluted manner.
So yeah. As someone who's been in the same monosexual mindset for a long time, I came to embrace my pansexual identity eventually. And so has Misumi!
Misumi's comphet ending probably wasn't meant to be tragic, but it sure feels that way to me. I guess her having boyfriends was supposed to imply she was bi? But it kinda came off as her forcing herself to date men and it never working out...