<human>: Throwaway because he loves reading r/relationships.

Are there ever any legitimate reasons for taking a relationship break? Does anyone have any experience taking a break that made the relationship stronger? Is my relationship with my SO doomed because I'm having these thoughts?

A bit about our relationship:
He's perfect. We've grown up into adults together, supporting each other the whole time. He's my best friend, my support whenever I need it. I love him- just thinking about him being hurt makes me feel terrible.

We've had our ups and downs, in fact just having made it out of a tough spot over the past 3 months. I kissed someone else when I was 19, but told him straight away. He forgave me for it, even though I was a stupid teenager.

The problem is that we spend a LOT of time together. We've been together for so long that I don't know what it's like to be single. 

Don't get me wrong, I'm happy. He's amazing, husband material. I'm just scared that as we get older we'll regret the fact that we never spent time apart. Although I hate the whole concept of 'the chase' and love the fact that I've never had to deal with crazies, it's something people have only told me about, not something I've gotten to experience. 

I guess I want a break because I'm scared I don't know who I am without him.

Is that a legitimate reason for a break? Are there *ever* any legitimate reasons for taking a break? Can a break ever 'work'? Will our relationship ever be the same again?

Can you summarize the given text in a few sentences?
<bot>: Under what conditions are taking a 'relationship break' okay? Does a break have to signal the end of a relationship?