Annamill -- I dunno... I have been in love many times, but I don't feel like I've fallen there. To me, falling is a very specific and concrete sensation that I can't disassociate from the physical act of falling into an abstraction.

But you may be correct about the origin of the phrase... Still, there are many things I do that I can't fight -- even if I want to, that have nothing to do with falling. Breathing, for example. Before my asthma was first diagnosed and treated, there were times I wished I could just stop the struggle for breath for just a moment, so I could rest, but I couldn't do it, no matter how hard I tried (thank goodness).

And, well, I've never been surprised by love... maybe that's just my personality, but I think I go through the world expecting to love everything and everyone (I guess you can thank those doctors and nurses who loved me in the first five weeks of my life outside the womb for that). Fear has suprised me, if that's my reaction to someone new, but not love.

Maybe, for me at least (YMMV), "Breathing in love" would be a better phrase, especially since it suggests an interplay of energies, and metabolisms...