They really had a love bond, but it was doomed from the start.
The only reason Angel even had the ability to fall in love despite the lack of morals for vampires, was because he was under a curse. As soon as he shared that one moment of truely happy bliss with Buffy, the curse was lifted and he became the bloodthirsty evil vampire he was in the beginning when he was first changed. As it turns out, Buffy had to eventually kill Angel in order to save the entire world...but that is another story.
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