Most middle-aged couples in Japan tend to express their dissatisfaction with their spouse.
ーMany married people complain about their spouses.
「多くの既婚者は配偶者の不平を言う」
married people で「既婚者」
to complain about で「〜について不平を言う」
spouse で「配偶者」
ーMost middle-aged couples in Japan tend to express their dissatisfaction with their spouse.
「たいていの日本人の熟年夫婦は配偶者への不満を漏らす」
middle-aged couples で「熟年夫婦」
to express one's dissatisfaction with ... で「…の不満を漏らす」
ご参考まで!
In Japan, many married people often voice their dissatisfaction with their spouses.
「日本では多くの既婚者が配偶者への不満を漏らす」は英語で "In Japan, many married people often voice their dissatisfaction with their spouses." と表現します。ここで "voice" は「声に出して言う」、"dissatisfaction" は「不満」、"spouses" は「配偶者」を意味します。
他にもこのように表現できます。
Many married couples in Japan express their frustrations with each other.(日本では多くの夫婦が互いに不満を表現します。)
It's common for spouses in Japan to complain about each other.(日本では配偶者同士がお互いに不満を言うのは一般的です。)