I have a theory! And nobody beat me to it while I was filling out the registration form (I hope):
Delilah "forgot" Marten's name on purpose to put any idea about this being more than a one-time-thing out of his head. She knows he's not used to casual sex and will therefore probably do something stupid like fall in love. "Forgetting" his name is a cruel but effective way to prevent this. He might feel angry/disappointed for a short time, but as he's the self-admitted "chillest dude ever", he'll soon get over it and there will be no awkwardness if they ever meet again. Well done, Delilah!
Welcome, Schwungrad! It is good to see that this discussion thread is bringing several lurkers into the open
I think Delilah's acid test was when she learned Marten was cool about the Tai/Dora relationship. That way, she knew they could have a one night stand without possible problems afterwards. She might not have planned it, but thought "why not" when Marten made the pass.
Marten asking for her phone number was just common courtesy, and gave her an opportunity to explain her position. It was way smoother than many other possible endings. I do not think she forgot his name on purpose, as it was not really necessary. But it was funny, nonetheless.
All in all, possibly a positive experience both for Marten and Delilah. They part as friends, with no hard feelings and no obligations. What remains to be seen, is how Marten's friends handle it, if they ever get to know:
Faye: "Marten, you slut! Don't you have any standards in life?"
Dora: "Finally got some relief, eh? I have seen it build up lately."
Hanners: "Eww! How can people even
do that?"
Pintsize: "Did you manage to take some pictures?"
Steve (thanks, Platypodes): "You just made it with the first chick in the room who caught your eye, and you're worried about your name? What is WRONG with you?"