[in which Angelus impresses Drusilla by giving her a fresh heart that he found in a "quaint little shop girl" ]
See - anyone who might have thought that Barnabas gorging himself on a blood soaked heart seemed farfetched should be changing that opinion right about now.
But anyway, a few episodes definitely come to mind that I think showed expressions of love:
[spoiler]Ep #191 - nothing proves a mother's love like trying to burn her child alive.
Ep #220 - love couldn't help but be in the air when two men move in together to set up house and one is completely under the domination of the other.
Ep #405 - what better way to display one's love than to curse your beloved to spend an eternity in which everyone who loves them will die?
Ep #411 - the ultimate expression of love is proving a person's love by allowing them the honor of being the first victim of their own curse.[/spoiler]
More may follow...