How to Say "Ex Boyfriend" in Japanese

元カレ

motokare[mo̞to̞ka̠ɾe̞]

The English phrase "ex boyfriend" is translated into Japanese as 元カレ (motokare).

元カレ refers to a man who was previously in a romantic relationship with someone.

Is there a formal and an informal way to say it?

元カレ is an informal, colloquial term used in casual conversation.

motokare

While 元カレ is used for exes, Japanese has a specific word 未練 'miren' for the lingering feelings or regrets one has for an 元カレ.
While 元カレ is casual, adding the suffix さん (san) to make 元カレさん can be used as a passive-aggressive or overly polite way to refer to an ex when one wants to maintain emotional distance.
In Japanese pop culture, the concept of the 元カレ is often linked to the trope of the 'first love' 初恋 (hatsukoi), which is frequently romanticized in music and drama as an unattainable ideal.

トムがメアリーの元カレだってことが、分かったよ。
I just found out that Tom is Mary's ex-boyfriend.
This sentence is useful for showing how to identify someone as a former partner using 元カレ.
Tatoeba #9518510 by small_snow, translation #7508782 by CK
私には新しい彼氏がいる。だけど、元カレはまだそのことを知らない。
I have a new boyfriend, but my ex-boyfriend doesn't know about it yet.
This sentence demonstrates how to describe a situation involving a current partner and an 元カレ.
Tatoeba #5845200 by joejames, translation #3416677 by Hybrid
元彼との関係は終わったけれど、友人として彼の成功を祈っています。
Although the relationship with my ex boyfriend ended, I still hope for his success as a friend.
昨夜は元カレと偶然会ったんだ。色々話して、思い出話に花が咲いたよ。
I ran into my ex boyfriend last night. We had a chat and reminisced about old times.
その人は私の元カレだよ。
Sono hito wa watashi no motokare da yo.
That person is my ex-boyfriend.
3 more sentences on Tatoeba

Yui and Hiroto are talking about a person they saw at a cafe.

結衣 Yui

あそこにいる人、知ってる？
Asoko ni iru hito, shitteru?
Do you know that person over there?
大翔 Hiroto

いいえ、知らないよ。
Iie, shiranai yo.
No, I don't.
結衣 Yui

実は、私の元カレなの。
Jitsu wa, watashi no motokare nano.
Actually, he is my ex-boyfriend.
大翔 Hiroto

そうなんだ、びっくりしたよ。
Sou nanda, bikkuri shita yo.
I see, that surprised me.

Sources

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