More unhappy / unhappier

It should be unhappier.

Oxford English Dictionary

unhappy

• adjective (unhappier, unhappiest) 1 not happy. 2 unfortunate.

— DERIVATIVES unhappily adverb unhappiness noun.

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TheFreeDictionary.com

un·hap·py (n-hp)
adj. un·hap·pi·er, un·hap·pi·est
1. Not happy or joyful; sad or sorrowful: unhappy over his friend's departure.
2. Not satisfied; displeased or discontented: unhappy with her raise.
3. Not attended by or bringing good fortune; unlucky.
4. Not suitable; inappropriate: an unhappy choice of words.
un·happi·ly adv.
un·happi·ness n.

More unhappy

eg. After moving to San Francisco, she is now even more unhappy than before.

2008-04-05 11:09:38 補充：
actually unhappier works too.... but it is more tricky to use it.
eg. Aunt Grace doesn't like unhappy kids! The unhappier you are, the less ice cream you'll get from her.

eg. Susan and Tom are fighting about who's unhappier.

兩個都啱
Give you some example:
I don't think women are unhappier than men.
Intelligent people more unhappy.

兩個都錯呀!!!!!!!
你呢題係關於英文既comparison
係comparison入面, 一D負面既字係會用less去代替架
即係話應該係 less happier

Should be more unhappier than

Joe is more unhappier than Peter.

unhappier unhappiest

更不快樂是 unhappier.
or you may use " sadder" instead.