something keeps you warm at night

Is 'to keep you warm at night' an expression? If so, what does that mean? And please give me some examples.

I added a conversation to give context. A woman is breaking up with a man because he is hiding a secret from her.

newbee said:

Is 'to keep you warm at night' an expression? If so, what does that mean? And please give me some examples.

I added a conversation to give context. A woman is breaking up with a man because he is hiding a secret from her.

MIKE:I don't want to be with someone who doesn't trust me. Maybe we shouldn't be dating any more.

Woman : Well, I hope that, your, you know, little secret keeps you warm at night because you're throwing something really great away to protect it!

Thank you!​

Click to expand...

This is a perfectly acceptable expression, but it really has only one use.
For a straight man, the best thing to keep him warm at night is to be in the arms of the woman he loves.

In the conversation above, the woman is saying that whatever his secret is, it will probably lead to their breaking up, so it had better be really important to him.

buggles (not a teacher)