After Rita died, and Lumen left, Dexter felt an emptiness. It wasn't the usual emptiness, it was the missing of being loved like Rita and Lumen did. It was the connection. Dexter had always thought of himself as independent, someone who was just fine being alone, yet he found himself missing that love.

Which is what led to him sitting at a restaurant for a date. You hadn't shown up yet, Dexter was beginning to get worried he got ditched, but then he saw you heading towards the table.