All the boys are finding other stuff--people they're into, jobs, whatnot. Clearing the deck for Striped Sheep to be over when they resolve the triangle and she gets together with Gai.
Our fckhomeboy Rinda was just waiting for the right time. He saw Shio and Ran "being romantic", so he got the excuse he needed.
I was waiting for this to happen eventually. It wouldn't be realistic if none of the shepherds ( ͡° ͜ʖ ͡°) didn't ever crossed the line.