“My Wife” (俺の嫁, Ore no Yome), typically rendered as “Mai Waifu”, is a subjective label that certain people attach to their ideal, fictional woman. The term isn't restricted by gender, so any person can use it regardless of gender or sexual orientation, but it is extremely dated.

In Japan, the term “Ore no Yome” (俺の嫁) was originally used by women in doujin circles, like several other terms with fujoshi origins, then it was mostly used by men. Naturally, this spawned a couple of similar, derivative terms. However, it'd be confusing if I just wrote them all down as the gendered pronouns would get lost in translation, so I've provided a small chart with those terms instead below:

While it might be tempting to use these terms for real-life people (e.g. idols, actors, etc.), many alternatives like “oshi” (推し), “gachikoi” (ガチ恋), and “riako” (リアコ) exist for such cases. Nowadays, it appears that otaku have mostly disowned the term, not just the yuri fans who say it clashes with their values, and dislike of the term has grown as it becomes more dated or obsolete.

Around the early 2000s, there was a scene in Azumanga Daioh where the main cast discovers that Kimura dropped a picture and he responds with “my wife”, which sounds like “mai waifu” in Japanese. For some reason, this caught on within 4chan and derivatives like “mai husbando” emerged. However, the term is also somewhat mocked as certain people believe fawning over a fictional character is silly.

The exact details of its spread is unknown, but it's rumored that “wǒ lǎopó” (我老婆, lit. “my wife”) had been derived from the Japanese term and started being used around 2008. Like the Japanese term, there are numerous derivatives which include terms like “wǒ lǎogōng” (我老公, lit. “my husband”), “wǒ nǚ'ér” (我女儿, lit. “my daughter”), “wǒ mèimei” (我妹妹, lit. “my younger daughter”), and so on.

• The kanji “yome” (嫁) means “wife” or “bride” in this instance, but can also mean “daughter-in-law”.
  • Similarly, the hanzi “lǎopó” (老婆) means “wife” in this instance, but can also mean “old lady”.
  • Chinese and Japanese use different characters since the hanzi “jià” (嫁) is the verb for “to marry”.
• At some point, the term “yome senzou” (嫁戦争, lit. “waifu war”) existed, though it's rarely used.
• The pronoun doesn't automatically suggest that a person is unwilling to share their love with others.

• Ore no Yome on Japanese Wikipedia
• Ore no Yome on Pixiv Encyclopedia
• Ore no Yome on Niconico Encyclopedia
• Wǒ Lǎopó on Moegirl Encyclopedia [ZH]