The app, Rela, set up in 2012, has around 5 million registered users, a cached version of its entry on Apple’s iTunes site shows.
But users began noticing last week that the app, along with its Twitter-like Weibo account and website, was no longer accessible, according to users posting on Weibo under the hashtags #rela and #relahasbeenblocked.
The service was temporarily suspended due to an “important adjustment in service,” Rela told users on its WeChat app account.
“Rela has always been with you and please await its return!” it added, but gave no details of why it was suspending service.
“This is discrimination against us lesbians,” wrote one user on Weibo.
“Not being able to open it feels like being jilted,” wrote another.
It was not immediately clear why Rela has been shut down.
The company did not respond to an email seeking comment. Apple did not immediately respond to a request for comment.
Internet regulator the Cyberspace Administration of China also did not immediately respond to a faxed request for comment on Monday, which is a national holiday.
In the past, the government has blocked sites it deems could challenge Communist Party rule or threaten stability, including Western sites such as Facebook and Google’s main search engine and Gmail service.
It is not illegal to be gay in China, although the country regarded homosexuality as a mental disorder until 2001. Many large cities have thriving gay scenes, but gay individuals still face a lot of family pressure to get married and have children.
Gay activists say deeply conservative attitudes towards homosexuality in some parts of society have contributed to occasional government clampdowns.
In April, another gay Chinese dating app, Zank, was also shut down after operating for about four years.
In a message on its Weibo account, which is still available, Zank said it had been accused by the internet regulator of broadcasting pornographic content and so had been closed down.
Still, gay dating apps are big business, even for Chinese companies.
Last week Beijing Kunlun Tech Co Ltd said it would buy the remaining stake in global gay dating app Grindr that it did not own.