imbitter

No feeling of remorse stole over her to imbitter the sweets of her triumphant thoughts.

And thus many are found who are silly enough to imbitter their own lives and the lives of others by such foolish superstitions.

He is always so preternaturally grave that she is curious to know if a smile—once indulged in—would imbitter or sweeten his face.

What would this be but to imbitter his reflections needlessly.

He made the best of things, overlooking the petty matters which some persons allow to wear and imbitter their dispositions.