But the fact that John knew that it was Sherlock’s birthday based on the fact that he got a text from Irene means that she and Sherlock don’t regularly communicate. They are people who knew each other years ago who on special occasions will send each other a text or say hi. It’s like when you wish a Facebook friend that you never talk to a happy birthday or a merry Christmas. It’s not really a relationship, it’s more like a polite social custom to someone you don’t really know anymore.
Yeah John, she’s out there somewhere. But Sherlock has had YEARS to follow that through and make something happen if he wanted to. But he hasn’t. Instead he’s committed his entire life to YOU, ya big dolt.
So do what Mary (AHEM YOUR INNER SELF) says and GET ON WITH IT already!!!