Where's Waldo?

I'm such a mother hen. My BIL (brother-in-law) lives with us. He has for 4 -5 years. I'm used to being his second mom. He's generally a simple kid. Sleep, School, video games, fast food. That's pretty much him.

However, he took the bar exam this summer and began sleeping somewhere else. WE kind of asked him a few times- only to be told it's none of our beeswax. So his mom asked and he claimed to be studying with a friend. But the bar's over and that kid still has not slept one night at home. He comes home every morning and gets a change of clothes, and checks mail and then leaves.

Who is the lucky lady? I am determined to know by the end of the weekend. Detective skills on!