Should the person be blocked?
If she wants to stop their behavior on social media then yes the person should be blocked.
If the person speaks to her about it at work, she needs to respond with something like: I am not going to discuss non work related matters with you, please do not speak to me about this again.
If the person persists, she should report this employee to HR or whomever is responsible for harassment.
workplace.stackexchange.com/users/93810/sf02
Should the person be blocked?
Yes.
Her social media should also be set to private so that only her name and profile picture can be seen by outsiders.
Personal information should be set to private or friends only such as her age, location, etc.
Should I talk to him?
No.
Should she talk to him?
No.
workplace.stackexchange.com/users/40006/Dan
Yes, she should block him, but she should also email him using work email saying:
Hey Bob, Just to be clear, I'm not interested in you, nor am I interested in being friends with you.
If you try to contact me one more time outside of work, I will report you to HR for harassment.
Do you understand?
It's important to do this in writing,
this way she has a time-stamped written record of her request with him.
This answer is partially based on a previous answer I gave to a slightly similar question.
On a side-note, blocking him on Facebook/Instagram won't remove his existing likes on her posts/pictures, but it will prevent him from seeing her posts/pictures on his timeline from then on, so it will ultimately prevent him from adding future likes/comments on her stuff.
workplace.stackexchange.com/users/14577/Stephan Branczyk
Should the person be blocked?
Yes she should do this if she doesn't want any more insinuations from this colleague.
If this starts to cross the thin line of harassment, she could also consider reporting the user.
Additionally, it is usually recommended to keep separate profiles for your personal and professional network users, so incidents like these don't happen (or at least happen less often).
workplace.stackexchange.com/users/73791/DarkCygnus
This man is harassing your girlfriend.
He keeps ignoring boundaries.
She should tell him verbally to stop contacting her on social media.
Once and once only.
She should not attempt to explain, justify, negotiate nor argue with him.
That opens the door for him to use DARVO .
This is where the offender attempts to Deny the behavior, Attack the victim and reverse the roles of Victim and Offender.
If he refuses to stop, document each and every time he attempts to contact her.
The diary she keeps these details in need to leave the office every day with her.
workplace.stackexchange.com/users/138/Tangurena
The best way to handle this is in stages.
First, she should talk to him.
The message should be clear (and kind).
If that does not work, she should block him.
If it comes to that, Stephan's suggestion of mentioning a report to HR is a good idea.
But hopefully, the first step is all that would be needed.
It is how most people want to be treated anyway.
workplace.stackexchange.com/users/36566/donjuedo
My girlfriend gets multiple friend requests, messages(emoji only) and likes on Facebook and Instagram from a colleague at work. The person is so assertive that after an unfriend, he continued with this behaviour even more agressively.   Should the person be blocked?  Should I talk to him?  Should she talk to him?
What to do when a work mate is unpleasantly pushy on social media?
workplace.stackexchange.com
<work-environment><colleagues><employer-relations>
workplace.stackexchange.com/questions/151961
workplace.stackexchange.com/users/107812/Darkov
She should start by talking to him. If they persist, then report them to HR. Document every time he tries to contact her and then block him. The first step should be for your girlfriend to speak with the colleague in question and ask him to stop contacting her on social media. To escalate matters further, she may want to report him to HR or block him on the site in question. Recording every attempt to contact her may also be useful when filing any reports.
First, your girlfriend should speak to the colleague in person and ask him to stop contacting her on social media. If the problem persists, you girlfriend should report the issue to the HR department or consider reporting the user to the social network in question. Your girlfriend should keep a record of each and every time her colleague attempts to contact her. Your girlfriend may want to consider blocking her colleague.