My youngest son's wife does that. Used to drive me up the wall. When they were first married they'd come over to visit every week and on holidays, and I'd start a conversation with my son and she'd act like I was talking to her - like, I'd ask him How's the new car or whatever, and she'd answer. Every single time. My favorite (

) is when my son would ask how my last doctor visit went, and if I said they found, say, a cyst on my elbow
or whatever, she had that, or she knows someone who did, and then I'd get to hear all about it.
After about a year of that I just had to let it go, cuz if I didn't I was never gonna like her. I could tell Liam didn't like it either, but he never said anything to her about it. (He did in private, but that's another story.) The only time me and Liam can just sit and talk about stuff we're really interested in is when we talk on the phone or he comes over by himself.