1st Corinthians 6:18
Flee fornication. Every sin that a man doeth is without the body; but he that committeth fornication sinneth against his own body. [KJV]
Therefore as I see it, one can sin against themselves.
If God not only looks upon sin, but is its sole author, having dreamed it up from no outside example, other than His own creativity to conceive of all manner of depravity and wickedness, and decreed and rendered it certain, then logically speaking, God would have sinned against Himself.