This isn't particularly a problem, it's just that some Cancers can get too emotionally attached. So if you see a Cancer laying on top of you when you wake up, don't be surprised. 

Plus it's hard for them to get over you.

Especially if you were like EXTREMELY close to them.

Here's a literal real life example:

Person A: *is sitting at a cafe*

Person Cancer: *walks up to Person A* Hello babe!

Person A: We broke up...remember?

Person Cancer: Sure we can break up emotionally but I'm not breaking myself up from you!

Person A: Can you not?

Person Cancer: I don't know, can I?

Example #2:

Person A: Babe, can you let go?

Person Cancer: No.

Person A: I'm just going to the bathroom.

Person Cancer: Then take me with you ^^

Literal real life examples.