You're the president of the US. You're feeling the need to have an affair, there are literally millions of women you could have an affair with... who do you choose?
Well, it's not like she was the only one. The Clenis spread the wealth.
But she was convenient. He didn't have to get up from his desk. He didn't even have to send the Secret Service out for takeout. Monica was like Domino's Pizza- delivered in 30 minutes or less, or the next one is free.
Bill looked into those big brown eyes and saw a bottle calf lookin' for a mama.