Ben: "We probably shouldn't tell Riley you hit on me."

He had her and then he lost her in the episode "The Lying Game" and couldn't get her back in the rest of the series.
Ben is such a compulsive liar, he just can't help himself. Instead of telling the truth, he spends all his time and energy thinking of ways not to do so, and ends up losing all. (Bonnie, his mother, of course is the Queen of the Liars)