I look at a lot of the "I miss you toos" as spontaneous bullshit toll booths on the relationship road. I don't mean it half the time but it makes for a happy relationship....on that day, at the moment.
Her: I miss you
Me: (oh u need hear that, okay well) I miss you too (shrugs)
My girl asked me plenty of times do I mean it everytime and I flat out tell her no. I ain't wired to need to be around nobody everyday. She is. She know I be lying half the time but she wanna hear it and she know
I know she just wanna hear it so......."I miss you too" it is (whatever, lol).
On the flip if she was with another guy who constantly was first with the I miss you's after a few hours away, she'd probably look at them like a mark.
Unfortunately, the little lies are conditioning for the guilt free bigger lies down the road. Guys get trained into the habit of lying daily to keep things on the up and up with their woman so later on it's nothing to say anything to manipulate the situations....to keep a happy home, on that day, at that moment.
Just how the world works...