What's Loki doing? Does he sleep with Hel in her bed? Is he crying there telling her that Sigyn doesn't love him? Wait, maybe not that... although anything is possible, Loki might be pretty emotionally exhausted by now.
I think it depends on culture. I've known several people from Europe who used "sleep with" as simply "sleep in a room with", and then they were a little surprised to hear it has an alternate meaning here... LOL