Why do people spend much time on cellphone than their books this days?
Because it's a computer in your pocket, you can do whatever you want

Don't you think much familiarity with our phones can affect our relationship?
If you spend more time on candy crush than talking to your family, yes
If you only talk to your family and you don't find a job because you don't know how to use facebook or linkedIn, yes

How many hours is idea for someone to use the cellphone per day?
How many hours is ideal for someone to use a pencil ? Don't know but if you are a drawer it could worth to spend more time with a pencil than a surgeon

why can't we do without our cell phone for an hour?
Well, with some imagination you can do something without a cell phone for an hour