Why does my MIL stare....

[Anonymous]

This is kind of a bad habit of mine, sadly!
People tend to stare at the person who is dominant/most attractive in a situation. Take it as a compliment and ignore.

[Anonymous]

Anonymous wrote:My thoughts are like someone already mentioned, shes watching you because shes trying to filter social cues and you are kind of like an interpreter for you to watch, or

She doesn't really follow or understand the conversation, but doesn't want to miss what you say, so shes paying very close attention. Or

She really wants to talk to you and is waiting for an opening.

This is my guess as well. I wouldn't say something, but if you catch her doing this you could be nice and bring her into the conversation.