Alyson Hannigan wished she had married Buffy The Vampire Slayer co-star ALEXIS DENISOF sooner - because she knew he was 'the one' on their first date. Denisof had to slow down the relationship and refused to even date Hannigan while they were working together. They eventually married in October 2003. Hannigan tells the New York Post, "I wanted to start dating right away, but he thought it was best not to while we worked together. "Being friends was great. But I still say we should have gotten married after the first date - I mean, we knew then."