This is based on opinion. Please don't list it on a work's trope example list.
Tear Jerker / Office Secrets
Every last one of the Normal Endings aside from Junya's has the protagonist and her guy acknowledging that they're in love with each other, only for the guy to gently but firmly explain that, for various reasons, he's decided that they shouldn't be together, and that it's better for them to remain strictly as co-workers and focus on business. In all such cases, it's painfully clear how much it hurts him to step back from their relationship, and the protagonist can only accept his reasons and try to find a way to deal with it.
Toranosuke's hits especially hard: he has to get himself drunk before he can bring himself to end things with the protagonist, and then there's the email that comes afterwards.
I haven't gotten this drunk in ages. To make it worse, I haven't slept in days... Do you know, I still can't sleep. I've been thinking about you and me. I think maybe if we'd have been in different companies, things might have turned out differently. But who knows... But thank you for everything. I'm still glad I got to meet you and I look forward to working with you still.