There were several things that Watanuki hated about his wedding. One was that he was even having one. Weddings in Japan were regarded solely as a ceremony for heterosexual couples and the idea of having two men join together was an absolutely ludicrous idea.
However, after a week of Yuuko-san's complaining and Himawari-chan's desperate doe eyes, even the strongest brick wall would have fallen, and fall hard Watanuki did.
(It was later found out that both women were under the authority of one Doumeki Shizuka. The devious bastard spent many a cold night on the couch for that stunt. It hadn't seemed enough to tamp down Shizuka's elation and smugness though.)
However when Yuuko-san had suggested that HE be the one wearing the shiro-maku, he had straight out refused and would not give in no matter how hard Himawari-chan begged and Yuuko-san teased (Why couldn't Shizuka wear the damn thing! He was the one who had experience with women's clothing!).
Watanuki figured that even after he had been released from Yuuko-san's employ and taken over her position, she still made sure to keep a few aces up her sleeve, in case of situations that required subtle cajoling.
So here he was scowling and wearing the bloody shiro-maku, and Shizuka was looking like he had just walked out of a historical film holding the red umbrella and in his hakama and kimono. While here he was, feeling like he wanted to die from the humiliation the bloody wedding outfit brought about.
His problems didn't end there though.
When Shizuka had smirked at him and handed him a tsuno kakushi, he had asked him what it was for.
"Your head."
"My head?"
"To cover the horns."
Once he had calmed down, he calmly told Shizuka that he was already embarrassed enough wearing a shiro-maku, let alone the headpiece that made it seem as though he deferred to Shizuka. Shizuka then calmly explained that it was his mom's and that she wouldn't have a proper wedding (with a GIRL) for her son.
Lifting his hand to his head for the fourth time to feel through the cloth on his head to see if he had horns he felt nothing, he could have sworn though…
Reaching the Doumekis' shrine (lord that was another story about the selection of the location for the wedding) Watanuki gave a sigh of relief when he realized that Yuuko-san had quite obviously pulled some strings to make it so that the shrine was completely deserted and that no one seemed to notice them outside the gates (How much would that one cost?).
Realizing that it had begun to rain lightly while the sun still shined, Watanuki stepped lightly past torii gates with a strained smile. Walking carefully (Himawari-chan had drilled it into his head of how to walk so he wouldn't trip) he made his way through the shrine behind Haruka-san (Lord knew how Yuuko-san had pulled that one off, but Watanuki predicted that despite his position, he would once again be indebted to the woman) who would be doing the priest work and two shrine maidens who had agreed to help with the wedding in complete secrecy.
The train of people following them to witness the ceremony was short, made up of Shizuka's parents and in the absence of Watanuki's, Yuuko-san, Kohane-chan and Himawari-chan.
The ceremony was short; the san-san-kudo was performed (Watanuki felt that Yuuko took more than her fair share of the sake). Watanuki at first objected to Shizuka reading out his small list of vows but Yuuko had told him about the importance of words, so he suffered through it as best he could, they placed a branch of the sacred tree in the sanctuary. It was poignant and beautiful and Watanuki still felt completely against this.
It when Shizuka and Kimihiro traded rings and kissed, that Watanuki decided that weddings weren't that bad.
Then he remembered the reception of over 300 spirits waiting for them and groaned.
Omake
When Watanuki later received the pictures that Himawari had taken of the wedding, one picture caught his eye. On closer inspection he was disturbed to note two protuberances had made themselves visible from underneath the white tsuno Kakushi that covered his head.