There are a lot of Japanese (high school/middle school) students who spend Christmas with their significant other.
小学生はほぼ含めていないですかね？
「日本の学生」は英語でJapanese studentsになりますが、この場合、普段middle school studentsやhigh school studentsと言います。
そしてThere are a lot of Japanese middle and high school students who spend Christmas with their significant other.
significant other=恋人
アメリカ人の友達に向けて言うなら、In Japan, people don't really celebrate Christmas with their families.（日本には、家族とクリスマスをあまり過ごさないです。） There are a lot of Japanese middle and high school students who spend Christmas with their significant others. と説明できます。
ご参考になれば幸いです。
In Japan, with many students, Christmas is a time spent as a couple
A couple' means two people who have emotional (and usually romantic) connections with each other. they ahve a special relationship based on them doing things together and sharing intimacies.
A couple'（カップル）とは、感情的なつながりを持つ（大抵は、恋愛関係にある）二人の人を言います。親密な関係にある人たちです。
In Japan, Christmas is an occasion which most students enjoy with their girlfriends/boyfriends.
Most students in Japan celebrate Christmas with their girlfriends/boyfriends.
Most students in Japan like to spend Christmas with their significant others.
If it is a fact that most students in Japan like to spend Christmas with their girlfriends/boyfriends, it means that they like to enjoy the occasion with their significant others. An occasion like this cannot be enjoyable without being with a significant other. The noun 'significant other' used in the third statement is used to avoid using gender based words such as girlfriend or boyfriend. The phrase is fitting in this case because it is gender-neutral.
So, you may say:
In Japan, Christmas is an occasion which most students enjoy with their girlfriends/boyfriends.
or
Most students in Japan celebrate Christmas with their girlfriends/boyfriends.
or
Most students in Japan like to spend Christmas with their significant others.
日本の学生はクリスマスを彼女や彼氏と過ごすのが好きであるということは、大切な人と特別な機会を過ごすことが好きということです。
このような機会は、大切な人と一緒でなければ楽しむことができないということです。3つ目の文の名詞'significant other' とは、彼氏、彼女のような性別で表す言葉を避けるためのものです。性別に関係のない言葉なのでこの場合ぴったりです。
In Japan, Christmas is an occasion which most students enjoy with their girlfriends/boyfriends.
（日本では、クリスマスはほとんどの学生が彼氏や彼女と楽しむイベントです。）
Most students in Japan celebrate Christmas with their girlfriends/boyfriends.
（日本のほとんどの学生は、彼氏や彼女とクリスマスをお祝いします。）
Most students in Japan like to spend Christmas with their significant others.
（日本のほとんどの学生は、大切な人とクリスマスを過ごします。）
In Japan, many students spend Christmas with their boyfriend or girlfriend.
Many students in Japan spend Christmas with their significant other.
The Christmas holiday in Japan is spent, among most students, with their significant others.
You are stating a fact that most students in Japan like to spend Christmas with their girlfriends or boyfriends. To say "significant other" is to generalize between girl or boy. Significant other can be both genders. In the second sentence "significant other" is used as a noun to avoid using gender words like boy or girl. All three sentences can be used to specify what you are trying to say.
In Western countries, students often spend time with their families over Christmas but in Japan, students rather spend time with their boyfriend/girlfriend.
Japanese students prefer to spend Christmas with their significant other.
Significant other = a gender-neutral way to describe a person with whom one has a romantic relationship.
This expression also doesn't indicate the exact nature of the relationship (ie. boy/girlfriend, partner, husband/wife etc).
It is a very politically correct way to refer to a romantic interest.
Significant other = 恋愛関係にある人をいいます。これは性別に関係なく使えます。
また、この表現はその人との関係を明確にしません（つまり、彼／彼女・パートナー・妻／夫など）。
恋愛関係にある人を指す性差のない言い方です。
There are many young people in Japan who spend time with their significant other during Christmas.
"There are many" は「多い」を表す。そして、"young people"を書いてる。この言葉は若者という意味です。この場合、学生を含まれるですけど学生じゃない人も含む。学生だけの場合、"students"は "young people" の代わりに書ける。
"In Japan" は「日本で」を指す。そして、"who spend time with their significant other" は「恋人と過ごす」という意味です。最後に "during Christmas" は「クリスマスのとき」と翻訳できる。
この英文は分かりやすいなら、ぜひ使ってください。
In Japan lovers typically spend Christmas together.
Lovers in Japan usually enjoy Christmas in each others company.
Couples in Japan usually spend Christmas together.
To explain that couples spend time together during Christmas, you can use the sentences above.
A couple is made up of two people who are romantically involved.
Couples enjoy spending time together especially when it comes to celebrating holidays.
Christmas is one of the biggest holidays celebrated the world over, lots of shopping happens during this time and people like to spend it with those they care for most.
「クリスマスはカップルで過ごすことが多い」は、上記のように言えます。
"A couple"（カップル）は恋愛関係にある二人を指します。
祝祭日はカップルで過ごすという人は多いですね。
クリスマスは世界で最も重要な祭日の一つです。この期間にはたくさんの人がショッピングに出掛けます。クリスマスは一番大切な人と過ごす人が多いです。
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