‘she tripped, but a pair of strong arms grabbed hold of her from behind before she hit the floor’
‘…she tilted her head back to look into his eyes, enjoying the feel of his warm arms wrapped around her torso’
‘…her hands intertwined behind his neck as their lips…
I come across this quite a bit. When you have to pause and puzzle out people’s positions and realize that some one turned around at some undisclosed point… I’ve also read fics that seem to have someone turning around several times without notice, it’s like a brain teaser~!