由前缀或后缀构成的否定意义,仍然当做肯定句.
此句unhapy虽然意思是不高兴,但仍然当做肯定句.
所以,按照反义疑问句前肯后否的规则,后面应该用,isn't he.
类似的例句还有：
It's too unfair,isn't it?
She is careless,isn't she?