Well, okay, I will engage in this because Candor. I know I'll get lost in debating, so I'd just like to point out all this should be taken as my opinion, not the law of the universe, so do read every point (besides the second which is a matter of Wiki rules) as if it said 'in my opinion...' in the beginning.
-Caleb was not working against Tris, but for Jeanine, which means working on capturing Divergents. This isn't 'against' because he actually believed it was good for everyone inculding Divergents and had no idea they would be killed (the movies do make it look like he did, but the entire part about Jeanine's experiments is pretty inaccurate); and it is not 'her' because it was about Divergents, not Tris in particular, and Caleb would've likely turned himself in if he were Divergent.
-Please express your dislike and hatred in decent, constructive ways. Following the Wiki rules, insulting and disrespectful comments (even if about fictional characters) should be edited or deleted, and their authors warned or even banned. Thank you.
-Love isn't rational and doesn't have to depend on what people do to each other and why either sensibly or emotionally. People's DEATH is, in my view, serious enough to save them from it even if you hate them with a passion. To actually be able to save someone from dying and not do so...well, there's no use in only caring about morals towards characters you like. I believe being good to people only has a true value if we can do it regardless of what they are like, it's not much of a virtue if we only do it when we like someone, frankly that sort of morals seems quite hypocritical to me. By being good I don't mean being used, again we are talking about saving from death.
-Feeling guilty implies being aware you've done a morally wrong thing.
-Abnegation rules shouldn't really be relevant because neither Tris nor Caleb have become Abnegation memebers, the latter doesn't even have an aptitude for it.
-There's nothing that implies Caleb doesn't love Tris, as said love isn't sensible and can't reliably be proven by actions or even intentions- it's perfectly possible to hurt someone you love even on purpose.