unaffected, disaffected

Unaffected or unaffected means unchanged or unaltered; not influenced or swayed--
We returned to find our campsite unaffected by the storm.
He went on talking, unaffected by her angry glare.

Unaffected may also mean free from pretention, sincere, or genuine--
He has charming and unaffected manners; he should be in public relations.
Try to read the part in a natural and unaffected tone.

Disaffected or disaffected means discontented, estranged, or no longer satisfied with--
He was interested in party politics for a while, but the last elcection left him disaffected.
He's collecting movies about disaffected youth and juvenile delinquency.

Now that you know that, you can say--
"His enthusiasm for gambling was unaffected by his losses; he only became disaffected by the cheating scandals."

Note--not to be confused with "disinfected", meaning treated to kill germs or disease--
She disinfected the bathroom with bleach and a good scrubbing.
Note # 2--"disinfectant" means a substance used to clean, meant to kill germs or disease--
Ordinary household vinegar is a pretty good disinfectant.