Despite what everyone(including me) is saying, you rly have to read the manga and decide for yourself. Possible relationships outside of KeiXBell are hinted at all the time and it's rly up to the reader to decide whether they see something there or not.(which is why I consider AMG a harem series!)
I said Skuld hadn't kissed Sentarou because Skuld mentioned 'me and Sentarou-kun haven't even reached that stage yet..'when the gate tried(or did) kiss her. I was thinking of that scene and how shocked Urd was that they hadn't kissed yet. So obviously the angel thing didn't count in anyone's mind.