First off HR IS NOT YOUR FRIEND
If you go to HR with this one of three things will happen
- You will damage or ruin your coworker's career
- You will damage or ruin your career
- You will damage or ruin both of your careers.
In two of the three possible outcomes, you damage your career.
HR would likely consider this a waste of their time as it was not a work function, did not occur on the premisis, and has nothing to do with the business.
Now, a bit about what HR is, and is not
HR IS NOT:
A place to tattle on your coworkers
The thought police.
for trivial matters
for anything outside of company purview
for settling minor disputes
for career coaching
a court of law
- The police
- YOUR FRIEND
Too many people make the assumption that they can walk into HR about any matter and have it magically settled with no consequences. If you walk into HR with something, there will be a note in your file stating that you brought up the issue. If this is a major issue such as harassment, theft, malfeasance, or ethics, this is a GOOD THING. However, if you bring in things that will waste their time and money investigating over trivial matters or non-work related issues, this will be a blot on your record and you will be labeled a problem employee, and you may be passed over for promotions, or in the case of mass layoffs, your name will at the top of the list.
Going to HR on matters such as what you described where
- It occurred off site
- It was not a work-related function
- Was not in writing and there is nothing but an unsubstantiated accusation on your part.
Will only damage your career.
You do not have to associate with this employee outside of work, and freezing this person out of social events is perfectly legitimate.
That said, you do have to be cordial and professional on the job until and unless the person does something unprofessional and actionable that can damage the company.