I never really say it. Ever.
I resent being expected to. I guess it comes down to what people are think you are saying when you say it.
If I say it to a girl does it mean I'm going to be sexually faithful to her? No.
Does it mean I'm going to sack off all my various plans and aspirations in order to make keeping her happy the sole purpose of my existance?
Not a cat's chance in hell. If she thinks it means those things she's in for a shock.
But then if I say it back (or if I think and feel it without saying it) it probably DOES mean that if it came down to it I'd die for her, or die if it meant she'd live...
So it's a strange one. I always think if it's true it shouldn't need saying. Then again I think maybe I can 'love' someone and do all the things to them that you aren't supposed to do to people you love...so who knows maybe I'm just a fuck up...