Consider the following Scenario :-
Boy overhears Girl saying something....
Boy think Girl is complaining/gossiping/.......... about him
or
Boy think Girl is enjoying someone else's company..
Boy gets Mad / Sad
Boy ignore Girl
Girl is Sad (don't understand why Boy ignore her)
A beautiful friendship/relationship is over.
- Seems like a scene from a movie/drama.

Apply it in real life - Replace the Boy/Girl with some names that you know or even yourself.
I believe it will happen to us at one point or another.
Why would this happen?

My thoughts?
Insecurity, lack of trust & courage
Insecure to think that maybe the issue is because of 'Me'. 'I' caused this to happen. Why bother to clarify?
Lack of trust in that person to stay true/loyal/faithful to the friendship/relationship.
Lack of courage to face up to the person. What if what 'I' heard/seen is true? 'I' don't think 'I' can face the reality.

It's good if you can approach the person and clarify on why he/she acted that way. Clear the doubts, forgive the person if need to and MOVE ON.
The benefits of doing this?

1. Bringing the friendship/relationship to another level
2. You don't need to keep guessing on what will happen if ONLY I clarified with the person
3. World Peace. Hahaha (Funny... But it's true!)