This. And I'm adding that he could have left even before, when he was still soulless. Drusilla offered him the chance to go back to his old life, to be free of feeding on humans. And even without Drusilla he could have still been evil, he just had to get some minions to work for him. But he didn't, because of Buffy and because he was starting to change.



I have a different theory about that. I don't think Angel cared to live and especially die as a human, he likes to be a vampire and the thing he wants the most is to be important. How could he be important if he was a useless human? And you know, I also believe that when he was sired by Darla he knew what it was about and wanted it. But that's another story

About Buffy and their relationship, I don't see much love on Angel's side. There is surely no evidence of it in s1, especially in the last episode where Xander tells him that Buffy has gone to face the Master. Angel clearly doesn't care that she's going to die and has no intention to help her. In fact Xander has to threaten him with a cross to force him to go. In s2 there are just few episodes and then they have sex and he loses his soul. In s3 he pushes Buffy to have sex with him, uncaring of the risk of losing his soul again and then after Amends they become a couple but he is clearly (and luckily! lol) unhappy and unsatisfied of their relationship. Buffy talks of leaving Sunnydale to go in a college in another city and Angel has no intention of following her. Why doesn't he? He has nothing keeping him in Sunnydale. He decides to dump Buffy just when she changes idea about the college and there are some scenes in those last episodes where he looks like he... I don't know how to explain, like their relationship - Buffy - is becoming to demanding. Buffy wanting him to go with her to the Prom, sleeping together without having sex, and the dream about getting married. He looks like the typical guy who doesn't want to get to involved, if you know what I mean I don't think that he doesn't care for Buffy, but I don't feel he loves her so much to be willing to share his life with her. Which is exactly what he tells her. So his leaving Buffy at the end of s3 just feels like something he really wants to do.



To me motivation is more important, so my answer would be no. In rl we can't really know why people do what they do, in fiction it's easier (or it should be). Angel's motivation are not so clear, because he says something and does the opposite. In Spike's case I see them more clearly