I don't think it is love in a relationship sense, more like love in a best friend sense. I remember Cera gets very jealous of Mo in LBT 9. This seems similar to her anger towards Ali. (I haven't seen 9 in a while, I may be wrong) I seem to remember her saying her anger towards Mo came from that the others wouldn't pay attention to her. So basically, Cera's jealousy and anger comes from fear of losing her friends.
I imagine that each of the GOF will eventually find mates, and that Spike will start talking by then (Although not neccessarily in every scene).
(Darn, I had a good theory about this, but I forgot it! Oh well. If I remember it, I'll post it.)