I felt the need to comment on a Mark Vernon post in which he mused over a behavioral change while travelling alone.
During that time, I noticed a massive increase in the frequency with which my partner and I exchanged the commonplace, 'I love you'. Normally we hardly ever say such things to each other at all.
He interpreted it this way....
It is only when physically apart that it becomes necessary to rehearse the fact of being psychologically together. Hence the exchanges of the phrase, 'I love you'.
I agree with the general reasoning, but as I commented there, I think there's more to it. It's a reflexive attempt to compensate for the absence of the physical "chemistry" that exists when you're with that special person. He did refer to it when he mentioned holding hands, but I think it's even more subtle and basic, almost a slight gravitational attraction that is so natural and pervasive that it's absence causes a feeling that something is off-kilter and you have to try to do something to maintain balance until it gets fixed.