Per the DC Comics Database in terms of BB/Rae on the show....
Titans head writer David Slack intentionally wrote Raven and Beast Boy as a "married couple", hence the relationship was one of deep loyalty and affection, but also laced with conflictive personality clashes. This "tough love" relationship between Beast Boy and Raven is continued in Teen Titans: Trouble in Tokyo, also written by Slack.
To quote fellow writer Rob Hoegee on the subject: "Raven only hits Beast Boy out of love."
It's been hinted several times throughout the series that Raven has romantic feelings for Beast Boy, but is simply too stubborn to admit it.
Yet, in issue #42 of TitansGO--the comics based on the show--Raven's Affection flirts with the changeling by saying, *rawr* "It's...you. How ya doin', handsome? Is that your coy way of asking me out on a date? Tee hee, you're such a flirt, Beastie-Boo."
Plus, from 2003 all the way up to the last 2011 issue before the reboot & beyond, the source comics have made BB/Rae a comic continuity canon couple (say that fives times fast; ).