Lifehack offers nine tips for dealing with people who bother you:
The best way to address the situation is to change how you perceive it and how you react to it.
Be clear on what you will tolerate and what you will not tolerate -- then stick with it.
People aren't mind readers, and sometimes they may not be aware that they are infringing on your space or taking up a lot of your time.
If the person does not stick within the boundaries, then enforce them.
If you just ignore them, they don't have a choice but to seek out someone else.
Most of the times, these people behave the same way around others too.
The next time you are with this person, get someone else into the conversation too. Observe how the other party handles it.
Often times, they act the way they do because they are looking for an empathetic ear.
Beneath the facade is really a cry for help.