I couldn't do that, though I remember being able to when I was about 3 or 4 years old. There was a lot of ill feeling went down after that, first with Mum and later with Dad, so by the time I was a teenager I kind of hated them. We reconciled to a fair extent later, but there remained a lot of space between us.
They're both dead now so it's too late to see if it would still be a problem. My sister's still alive, can't say it to her either. Even by email.....she sometimes puts it at the end of her emails to me, and I feel guilty about not reciprocating, but somehow I can't, not even in writing.
I'd like to know why.
It's obviously nothing to do with the demand for an immediate response - I can take a couple of days to reply to an email if I like. Just doesn't feel right. Maybe it's the pedantic Aspie thing, being unable to define it.......to me, "I love you" is usually a pretty meaningless thing to say, and I've heard partners say it to me but then go and do stuff that makes me feel they didn't mean it. Some people are too glib with it, and seem to try to use it cynically as a placebo or an ingratiation strategy, so I suppose I might be seeing it as unworthy of me.
On the other hand, I'd hate to say "I don't love you" to anybody I particularly cared about. It just seems so hurtful to say that. Curiously I can say "I love you to bits," though I reserve it for people I'm not particularly close to....it means that I dig them because they amuse me, which is nothing like so heavy as "I love you," and some people really do cheer me up wonderfully, so it feels right for me to tell them that I love them to bits.