What time do you train? If it's late, that can lead to poor sleep.
Maybe you have a small bladder.
Maybe you need to address the things you are worrying about. I'd say, start with the girl thing. Get one and do stuff with her before you go to bed. You'll sleep quite well.
Is this issue actually affecting your training or are do you just think it will? That could be stressing you out too, "Oh no, I woke up, now my squats are going to suffer. Gotta sleep."
All I can say is that many of us lift in the evenings and cram as much protein in our bodies as we can before hitting the sack. Sometimes we get solid sleep. Sometimes we don't. I doubt the milk is keeping you up. Besides, what do you give a baby when they wake up in the middle of the night? Milk! Knocks 'em out. And, really, we're all just a bunch of big babies.