Happier means more content than before or than somebody else. Much happier, happier now, happier without it.
It is the comparative of happy, formed by changing the y to i and adding -er, which is the rule for two-syllable adjectives ending in y. Happier with means more satisfied. Note the happier the better; and that in British speech I would be happier if is one of the standard polite ways of raising an objection without appearing to — it means I think you are wrong.
1adjectivehappierMore content than before or than another.
“She was happier in the second job and paid about half as much.”
happier is a comparison of contentment.
Practised in Word Building