You’re coming here because you are being pushed to your limits and want to know the best course of action, seeking advice from the community at large. That’s great!
I consider much of this to be a comment, but my lack of rating in this forum won’t allow me to attach it to your question, so please allow me to expand on some things to consider. I would look at it less as letting your manager know and more as getting input from your manager whom should be trained to handle inter-personal conflicts.
Something to consider is that there could be more than meets the eye. For all you know the person could be going through something personal that has nothing to do with you. People have their own struggles (relationships, deaths, financial) and are riddled with disorders (bi-polar, depression, etc), which makes it difficult to interpret even what you think you know.
The point you want to focus on (at first) is not that there is a problem, but that you are looking forward to establishing a solution and to learn how you could better address the situation. You would like to know the best way to move forward and not necessarily raise a complaint. There are perhaps personal differences that are bleeding into your working relationship and knowing where to step next is a delicate move.
Because there is more to the story, more than you could obviously elaborate on here, the best point of advice will be from someone impartial that can hear the whole story and ask questions where you may have left holes. Who the advisor is, will ultimately be left to your better judgement as there are a lot of things to consider (comfortability, trust, role, etc). Depending on your personal and working relationship it could potentially be your boss, another superior or senior employee, life coach, psychologist, Ombudsman, or HR. If you ever do wish to raise the issue (more than seeking advice) it's important to be seen as someone other than an instigator.
Without all the details, I couldn’t honestly rule out that the problem could still be you, or it could be all in your head - not saying that you’re wrong, but the outsiders perspective should not be to automatically trust the storyteller. That said, being a problem-causer rather than a solution-maker will certainly be more frowned upon.
We, hearing this situation, have no history of the person, so if the person hasn’t had any issues in the past, they have tenure in their favor and you don’t. But then there are things we don't know.. do they have a pattern of this time of behavior? Have other people raised complaints? Is there something you can do to adjust? Are they the type of person that are open to ideas? Whatever the case, be innocent and open to ideas, but with whomever you speak, also be assertive. State that you don't want to upset anyone, but care about your career and don't want to jeopardize that. It's a fine line, but you have to express concern without offending someone or being seen as a trouble-maker, while instilling your own value and self worth.
Before talking with anyone else, though, it might be worthwhile to have lunch with the person and identify that your relationship seems to have got off track and if there's anything you both could work on to improve that. Maybe don't confront or raise all the problems at once, but start the conversation to establish a rapport and keep notes on that (your efforts and the outcomes) as they will ultimately better describe the situation and your efforts if push comes to shove.
