He's talking to the group, not specifically to Teer. It's pretty clear in Epiphany that that he and Teer did have a physical relationship -- that's what the fade-to-fireplace business is about. Just because they don't show the actually sex-after-kissing on PG television doesn't mean we assume they don't have it. Otherwise no character on Stargate ever had sex ever. Or went to the bathroom, for that matter. Do we ever see Teyla eat the food on her tray? I don't think so. That doesn't mean she's secretly a Wraith.

And if you didn't watch The Tower clip I posted (he doesn't just stare at the boobs, he actively pursues sex with Mara), then you aren't forming your opinions based on canon. In fact, if you haven't watched all of canon, then you really aren't informed on John Sheppard. He flirts in the mess with Esposito. He kisses Larrin in the Travelers. He was *married* to Nancy (Outcast) and him being asexual wasn't what broke them up, but rather his covert missions. She couldn't take the secrets anymore, but now that she works for Homeland Security and has to keep them from her husband, she tells John she understands what it was like for him.

There's a wealth of evidence in canon that disproves your theory, but that doesn't mean people can't write him as asexual or enjoy stories with him ACE.

Sadly, there were show/political reasons why Joe Flanigan wasn't written more Sheppard-centric scripts or a love interest of his own.