(Sorry if this doesn't help or is hard to understand-)
Step-by-step explanation:
Every person is different and have a mind of their own, so their reaction will be different from others depending in the situation. Each and every one of them have a fear of something, even if they don't want to admit it, something is always bothering them at the back of their minds.
And if one of their fears (such as; embarrassment, failure, abandonment, or death) is present in the situation at hand, they will freeze up and not know what to do. The human mind is something strange and it can be difficult to understand how someone, or yourself, feels about something and cause them, or you, not know what else you could do to help.
Fear can cause someone to not do something they desperately want or need to do, especially if the events are moving to fast for them to understand and makes them panic, sometimes even leading them to worry too much if it's their fault that they couldn't help.