It's Rem. Who doesn't love Rem? I mean be honest; if you could have a beautiful demonic maid who was madly in love with you as her master, or even her friend, would you turn the opportunity down? Moreover would you turn her down if she was waiting for you on your freshly made and laundered bed looking like this?
No. No you wouldn't. Enjoy yourself, you've earned it, and she's definitely worth it.