Ted is pretty certain he's gonna have to tell them eventually, since he can't imagine Joan leaving his life. But even so, it's a sensitive subject, and Michelle might have complicated feelings, and he wants to be very conscious of introducing Henry to a girlfriend, and how he handles it. So today is definitely not that day.

He smiles at Joan and then calls. After a few moments he smiles happily, as Henry picks up.

"Hey bud! How you doing? ... Oh really? ... No way." He laughs a bit. "Yeah, I'm good. I cooked bierocks today, remember those? ... No, I didn't burn them. I did that one time, kiddo." He turns a little and gives Joan a dramatic eyeroll before he focuses back on the conversation.
"Yeah, I bet. ... Nah, I just wanted to check in, tell you I miss you. ... Yeah, I love you too. ... Tell your mom hi from me? ... Alright then, bye bye."