Ex-Partner, Former Partner
noun
Your origin partner is a partner you had originally, but don't have anymore. In other words, this is your ex-partner or former partner. Like in English, this word is fairly formal, and it covers any kind of ex-partner, including business and romantic partners.
もとぱーとなー, もとパートナー
This uses the kun'yomi of 元 and then it's just kana, so you should know how to read this!
元パートナーからテキストがきた。
I got a text from my ex-partner.
あ、それ、元パートナーのネックレスといっしょだ。
Oh, it's the same as my ex-partner's necklace.
これは、ふじ山で元パートナーとスキーをしたときのビデオだよ。
This is a video of me skiing with my ex-partner at Mt. Fuji.