When Elisabeth Boyd went through a breakup in 2014, she decided to block her ex on social media to spare herself the pain of seeing his posts. She blocked him on Facebook, Instagram and Twitter.

It wasn't until about one year later that she realized there was one social network she had missed. She logged onto her LinkedIn and saw her ex had just started a new job.

"I didn't realize I hadn't blocked him on there until I got a notification," Boyd, 33 and an executive assistant in Los Angeles, told CNBC on Facebook Messenger. "At that point I had already moved on. Of course, it didn't stop me from snooping a little!"

Boyd's digital breakup and exception for LinkedIn appears to be a common trend among millennials dating in the age of social media. While many who date say they tend to unfriend, unfollow or outright block their exes on Facebook, Instagram, Twitter and Snapchat after a relationship ends, LinkedIn seems to be one social network that's breakup-proof.

For many like Boyd, they say they simply forget about LinkedIn, which is a professionally focused social network that was acquired by Microsoft for $27 billion in 2016.

Others say they make a conscious decision to leave their exes on LinkedIn. One major reason is because LinkedIn is more limited in the amount of personal content that one can post. While other social networks provide constant updates or multiple photos and videos of an ex, LinkedIn does not.

"With exes it's hard to watch their life on social media, but LinkedIn is so much less real-time," said Abby Homer, a 24-year-old communications professional in San Francisco, in a Twitter message. Homer said she, too, was blocked by a long-time ex-boyfriend after a rough breakup on every social network except for LinkedIn. "You really just see very specific milestones."