Space [&] Time

"I need my space", "We need some time apart"

How many of us are guilty of saying these things every time our relationship becomes to difficult to handle?

If you answered yes, then answer this question, Is space and time apart necessary?

Apart of me believes that it is necessary because it gives two people time to miss each other; it also gives two people time to work out things on their own. When I try to answer this ? I always contradict myself because I also believe that it's not necessary. If you want a unbreakable relationship you should be able to work out your problems together; if you start to get in the habit of working things out on your own then you'll never be able to overcome anything together; if you can't overcome obstacles in your relationship with your partner then being in a relationship with that person is pointless. No matter how many times I try to answer this question I can never come up with a clear answer...What do you guys think? Is it necessary to ask for space when things become difficult in your relationship?