He smiles at the answer, reassured and touched by the conviction and the love in it.

"Well, I don't really see the appeal in the first place - which is fine, you know, we can like and need different things," he says, not wanting to come off as judgy. "But, you know, maybe there was something you got out of it that you don't get from me. That would be okay too. I don't have to be everything to you to still be important to you."

It's why he's also not jealous of Sherlock. Hinging absolutely everything on your partner isn't healthy, no matter how much you're capable of giving each other. And it doesn't take anything away from their relationship, because he truly believes that their capacity for love increases with each person in their lives.

And personally, Ted already had a slightly difficult time satisfying his need for sex with someone he wasn't romantically involved with, and that would only be even more true when he is already in a romantic relationship. But that doesn't mean that's true for Joan. The most important thing to Ted is protecting the trust between them, that they're honest with each other.