Xander would never cheat on Anya, that was for damn sure. He loved Anya. But cheating as defined in Websters was to be sexually unfaithful without the other's knowledge. And Anya had emense knowledge. It would have been hard for her to not have knowlegde, seeing as she was the one to first suggest it.
It didn't bother him that she wanted to see him have sex with someone else. Millions of dollars were made off that concept a year, the porn industry flourished under the idea of watching others have sex. And it didn't bother him that the sex she wanted to see was with another male. After all, she was perfectly willing to let him watch her have sex with other women.
The problem was in both cases that there were no obvious potentials for female sex or male sex. Or rather, there were no girls for Anya; Tara and Willow being very monogamous. There was a clear boy for Xander, but he would actually have to ask. And he just didn't want to.
Unfortunately- luckily? it was hard to tell- Ayna had the most blunt attitude of anyone he had ever met. Xander woke from a post-work nap one evening and saw Spike standing there, regular black tee wrinkled and tucked into a tough belt.
"What? Need money? I'm not giving you squat, go bother Giles. Who let you in? Don't make me do another protection spell, because I swear-"
"The demon bint told me you wanted to talk to me." Xander couldn't possibly talk, he just rolled over and buried his head in the pillow.
"Actually, that's not what she said. She said you wanted to interlock parts. Took me a mo' to figure her out, but thought I better come over here to see if this was some weird spell thing. The witches bugger up, make you insane?"
Xander was sure if he only got his head far enough into the fluffy pillow that Spike would go away. It was probably a strange sight for those standing up, seeing a grown man snuffle and twitch, but he didn't much care. All that mattered was that he went away, and he didn't have to have this conversation.
"I take it from your extreme horror the demon bit got her lines crossed?"
"I most certainly did not!" she shouted from the living room, and Xander let out a moan. "He wants to interlock parts. Xander would very much like for you to fuck him, because he's already fucked me and knows what that's like but I won't fuck him because a strap on is a waste of money if we're not sure he'll like it. It is bad to invest money in things that might not be used."
Oh, god. Why him?
"From the mouths of frugal babes, huh."
"Just because you're mysterious and strong doesn't mean I want to have sex with you." Xander shouted, getting a mouthful of damp pillow for his troubles.
"He also thinks you're small with pretty muscles." Ayna added helpfully.