What do guys mean when they say, "I love you?"

I don't mean situations where he says it to get her in bed or because she said it first, etc. What I mean is: does it mean I really care about you and have loving feelings? I love you so I'll never leave? I want to marry you? The reason I ask is that I've heard that guys tend not to declare love as easily because to many of them it also implies something more, like some form of future commitment? Is this true in your experience?