My mom and dad are close, but when mom wants to go out with her
friends, she gets her alone time, and when dad wants the same, he
gets it too. Out of respect for each other, they'll say who they're
going out with and what they'll be doing. They don't question each
other in detail. I like that kind of freedom and mutual
respect.
Some of us need our private time to think about stuff, to just
enjoy the peace and solitude, to calibrate our internal radars...
stuff like that.
It depends on how the need is communicated, of course. If the other
party is assured that should there be an urgent need to, one is
contactable even during one's private time, things should be fine.
I guess one has to work out with one's SO how this issue should be
handled so that no one feels upset over it.
My ex and I gave each other a lot of alone time. During the alone
time, I got to catch up with my other friends, spend time doing my
hobby, pay more attention to my cats, etc. Sometimes, indulge in
whimsical stuff like sitting by the wide open kitchen windows,
enjoying a nice glass of iced lemon tea, looking at the stars and
just daydreaming. 
All said, if a guy is so insecure that he can't even bear the
thought of me going off for a few hours of alone time, then he's
really not my type! I won't be able to tahan the sticky-ikky sort
who clings to you 24/7!
And yes, I have
shirked off such guys before back in my schooldays!
The recollection still
makes me shudder!
