Some married men enjoy the flirtation, but then don't intend on acting upon it. Like it's stated above, some enjoy the attention and it gives them an ego boost. But I wouldn't worry at this point about why he flirted when he's married. He's married. Also, a word of advice: I wouldn't go looking for a romance from within the office. It can lead to a messy situation especially if it doesn't work out. A cardinal rule to follow at work: don't date at work and don't have office romances. I find it's a good rule to stick to.