Against you, you only, have I sinned. Really?

Psalm 51:

for the director of music. A psalm of David. When the prophet Nathan came to him after David had committed adultery with Bathsheba.

4 Against you, you only, have I sinned and done what is evil in your sight;

Did not David sin against Bathsheba's husband as well?

The prodigal son acknowledged in Luke 15:

21 The son declared, ‘Father, I have sinned against heaven and against you. I am no longer worthy to be called your son.