It's nice because you are convinced once again: you have such a big and strong man! and the truth is almost a hero for this reason alone! And the girl immediately feels like just Thumbelina and a princess rolled into one.
Plus, such pampering with a girl in his arms is still an element of some kind of game, "tomfoolery" (exclusively in the POSITIVE sense of the word !!!), that is, you understand: he is so big and strong (perhaps , brutal), but with me he is ready to be simple, open, emotional - not the same as with everyone! It means that I am very close and dear to him !!
And about "I'm fat, heavy" .. obviously, the girl says this only to hear the opposite: "No, you're just a fluff / slender / baby!" This is from a series of passing casually "you don't love me .." (the only true reaction of a man: I love of course !!), "you don't care about everything" ("Of course not, dear, let's discuss and decide everything"). The main thing that a man should not do in this case is to be silent! In no case) Continue to drag it on your hands in the given / desired direction and convince that it is lighter than a cloud, lighter than air and even lighter than the smallest fluff!
It should be noted that the average man can lift two of his weights, while a woman can hardly lift her own. Therefore, a woman who picks up a man in his arms is perceived as a kind of heroism.
Because the relatively unusual sensations are reminiscent of childhood, I think. You feel small, but at the same time you know how much you really weigh and worry if the "porter" will rip your back)