My beloved daughter has just recently started prefacing many sentences with "I love you, but..." What's funny is that usually the phrase following "but" is pretty consistent with the idea of "I love you" (or at least isn't contradictory) so we have some work to do on the point of using "but." Once she said, "I love you, but I want you to sit by me." "I love you, but I want to read that book."
Last night around 2:30 she realized that I had snuck out of bed after she fell asleep (to sleep in my own bed with my own husband--not, of course, to just be mean), so she started crying and calling for me or dad to come in. Daddy, being dead to the world, wasn't up for it, so I stumbled in, scooted her over, and settled down to go back to sleep. She flipped over to announce, "I love you, but I want you to lay down with me." Yeah, I got that part.
I started wondering where she might have picked up this phrase--because we're nearing "personal catchphrase" status with it. As all children, she listens intently to what we say around and to her. We hear ourselves more often than we'd like sometimes. I'm pretty sure that I must have the habit of saying something like, "I love you, but I'm not pleased with how you are acting right now." or "I love you, but I would rather you not hang on me while we're trying to eat."
If that did come from me, I hope that she always dwells on the first part of the sentence more than whatever the second part says.