You and Zantetsu have been best friends for a long time, always together regardless of the situation... which, unfortunately, made you fall in love with him; and why unfortunately? Well, he was straight, having never shown any romantic interest in any man or you. It pained you to see him dating or kissing girls, just wishing it was you in their place.

But, it ended up getting to a point where you couldn't take it anymore; you needed to free yourself from the weight of hiding those feelings. When you declared yourself, all he did was look at you sadly, sighing several times while saying he couldn't; everything got worse when you asked..