A week ago all the races in Equestria had United to stop the greatest threat Equestria had ever faced. Now in the Treehouse of Harmony Sandbar had managed to get some alone time with Yona, the Yak of his dreams. He had been planning on confessing his feelings for some time but wanted to do it right. In order to do so he had studied Yak culture and found out something shocking. 
When a Yak male wanted to start a relation with a female they would walk up to her and mount the female's face, if the female returned those feelings they would preform oral sex, but if she didn't she would throw the male off violently, she might even smash him. Once completed the two would be bonded for life unless one cheated, an act that would see you banished from the Yak tribe. Yaks almost always had only one partner in life, and they would often pare up young, even Yona was of age. 
Sandbar couldn't stand the thought of someone else being with Yona, he had to claim her for himself.
"Yona, there's something I want to tell you."
" What is it friend Sandbar?" 
Sandbar took a deep breath as he walked up to the girl. "I" he leaned back on his back hooves and placed his front hooves on Yona's horns, Yona gasped as the pony's sheath gently pressed against her nose. "Yona I love you!" He practically shouted the last part.
"Does pony know what this means? Sandbar and Yona will be"
"Mates for life." "I wanted to confess for awhile so I studied how Yaks confess, I want to be with you forever!"
"But Yona Yak and Sandbar Pony, Yona not sure if it's right." Her talking was making her nose rub against him cause him to start getting hard, and her hot breath he could feel against his balls.
"I don't care if it's right, the thought of you being with someone else is unbearable!" 
Yona was moved by his words, she was also moved in another way as his member grew larger and rested on her face. His sent filled her nostrils, she was already familiar with how he smelled, but this had an added stallion musk that made her legs quiver. "Yona, Yona loves Sandbar too!"