前 + Relationship Noun
前女友 (qián nǚyǒu) means "ex-girlfriend." The prefix 前 (former) is placed before 女友 (girlfriend) to indicate a past romantic relationship. This pattern extends to other relationships as well, such as 前男友 (ex-boyfriend) or 前妻 (ex-wife).
他跟前女友分手已经两年了。
Tā gēn qián nǚyǒu fēnshǒu yǐjīng liǎng nián le.
It's been two years since he broke up with his ex-girlfriend.
在街上偶遇前女友,气氛有点尴尬。
Zài jiē shàng ǒuyù qián nǚyǒu, qìfēn yǒudiǎn gāngà.
Running into his ex-girlfriend on the street, the atmosphere was a bit awkward.
她不太喜欢男朋友老是提起前女友。
Tā bú tài xǐhuan nán péngyǒu lǎoshì tíqǐ qián nǚyǒu.
She doesn't really like that her boyfriend always brings up his ex-girlfriend.