I don't think Sherlock is 'in love' with John, but I do believe he loves him. He's probably moving out of Sherlock expected to come back and have everything go right back to normal. He is sad because it can't be his way.
I feel her pain. I kinda feel bad for the mom though. Having to look for the nonexistent pieces that would mend our sad and broken fandom. Wow, that got deep quickly.<<< calm down seriously I don't want to start crying