I liked Xander and Cordelia together as a couple and I thought it ended way too soon We never really found out whether they had a future or not because they did not date long enough. What we saw already showed that they were good together and good for each other. Opposites make the best couples with the best relationships as long as they have love to bind them.
Yes! They improved each other in their relationship. When they had that bullcrap storyline of Xander cheating on her with Willow, it made no sense whatsoever because we've always seen Willow as his little sis. He ignored Willow for Ms. French, Buffy, Ampata, and Cordelia. He basically chose to be with Cordelia over her in Innocence. To me, it would be out of character for Xander to even have an interest in her after what we've seen. I've considered that as crappy writing and unnecessary writing. In Bewitched, Bothered, & Bewildered, Willow and Xander had this conversation:
Willow: "How long have we been friends?"
Xander: "A long, long time. Too long to do anything that might change that now."
Willow: "But friendships change all the time. People grow apart. They grow closer."
Xander: "This is good. How close we are now. I feel very comfortable with this amount of closeness. In fact, I can even back up a few paces and still be happy. See?"
Willow: "I want you, Xander..... to be my first."
Xander: "Baseman. Please tell me that we are talking about baseball."
Willow: "Shh. We both know that it's right."
Xander: It's not that I don't find you sexy. "
Willow: "Is it Oz? Don't worry about him. He's sweet, but....he's not you."
Xander: "Yes, he is. And you should go to him 'cause he's me."
[Willow starts to kiss, bite, and lick Xander's ear.]
Xander: "I---I---I don't want to use force."
Willow: "Mmm. Force is OK."
[She continues to kiss, bite, and lick Xander's ear.]
[Xander has had enough, and is deciding run from Willow.]
Xander: " Th-That's it! This has gotta stop. It's time for me to act like a man. And hide."
[Xander is running away from Willow. And the scene ends.]
Xander pretty much says the same thing in Inca Mummy Girl, but Xander was talking to Buffy about it while Willow was eavesdropping on their conversation.
Xander didn't do the spell for Willow (or Buffy), he does it for Cordelia. He doesn't show any interest in Willow after this episode. In BB&B, it was obvious that Xander still cared for and had feelings for Cordy because of the lengths he goes to protect her. Xander cheating on Cordelia with Willow never made sense to me and I deem it as unnecessary writing. The writers could have had developed the Xandelia/Cander relationship because he seemed very happy with her, he looked happier with her than with Anya. He wasn't as embarrassed by Cordelia like he was with Anya. Plus being with Anya made him look like a hypocrite whereas Cordelia didn't make him look like that. Xander&Cordelia had A LOT of chemistry and passion. Nothing beats the original. Datherine(Damon&Katherine from TVD) had the better relationship than Dullena(Damon&Elena from TVD). Damon looks like the sweet White Knight in the Datherine relationship(she did love him), but he looks like a hypocritical jerkwad in his relationship with Elena. Xanya and Dullena are both carbon copies of the Xandelia and Datherine relationships since Anya was the new Cordy to Xander, and the TVD writers had to vamp up Elena so she can be another version of Katherine in the Delena(Dullena) to Damon. Xander looked physically better in the Xandelia relationship. Cordy most likely bought him some clothes. Cordy*Xander's relationship started off as slow like the way Buffy&Angel's relationship was unlike 2 other relationships.
If Cordelia were to stay on Buffy the Vampire Slayer and still be with Xander, then Xander would be less likely to bail on his marriage/wedding with Cordy. It would've been nice to see Cordelia in a wedding dress, and Willow, Buffy, and Dawn would have had better looking bridemaids dresses. The wedding would look demonless, which would impress Xander's parents and the rest of his family since there would be less of a chance of a brawl. Buffy wouldn't have the need to kill Cordelia like the way she did with Anya. Xander wouldn't be looking like a hypocrite jerkwad to Buffy.