That being said, it's not just giving thanks that he has living proof that settling down is where it's at that makes him pal around with Ted. He also comes in handy when he wants to talk about something and not have a distorted version of it repeated back to him by a crazy woman jabbing her finger in the air about something she doesn't actually understand. It's bad enough that Elly's paranoia and truculence run away with her when it's just the two of them talking; I can only imagine how much it must suck when Elly has to deal with second-hand information. Since Ted tends to talk down to women, John can say things without penalty.
This leads us to his other use: watching Elly get pissed off at him. He knows for a fact that Elly hates him like no one else because he doesn't admit that he should