Könnte mit dem OP … an Brüste oder Pobacken erinnert? (#16)
Unless there’s some clue in that direction embedded (somewhere else) in the text, I’d be inclined to negative that.
But “cleavage” is a useful reminder of the fact that “to cleave” is not only used transitively, but also intransitively as in the OP, in the (intransitive) senses of to split, to part, also in geological/mineralogical contexts like “Good quality slate cleaves very thinly making it ideal for roofing,” “When you cut a crystal - like diamond - you get nice smooth faces because the crystal cleaves along particular crystal planes,” or this use in cookery " ... put about two teacups of water and plenty of salt and pepper over the chicken, then let it cook until the meat cleaves easily from the bones," or, again, figurative uses, e.g., "Yet her life cleaves in two as she begins an affair with Gould while seeking to maintain her life as a dutiful wife and mother."
(My hunch, sorry now I’m repeating myself, is that this sense is involved in the OP conflated in the character’s or the author’s mind with the simultaneous cutting or carving that gives rise to this cleaving. Needless to say, not necessarily the author's idea ... ;-)