Ease is relative. I can make the argument and the married or folks in relationships here may choose to add different things to this, but after a while it can get tiring trying to wake up to a different face or an empty bed. While some guys never commit and that's within their right, even some of the season bachelor's like George Clooney give up the ghost after a while.
Beside, the more loose with the ladies someone is (or with whomever they like as partners), they're more likely to have a Charlie's Sheen moment...
Posted approved via Moto Maxx