Since when do atheists expect the religious to act rationally? I don't even operate rationally all of the time and I'm actually making an effort.  
 
The religious pretty much get free pass to irrationality land. Why expect them to act consistently with their beliefs? 
 
I have yet to meet a person who doesn't operate contrary to their professed "beliefs" on a regular basis. I've run into leather wearing animal rights motivated vegetarians, anti-war pacifists advocating the execution of neocons, and objectivists with a irrational religious furvor that would put a moonie to shame, people who think the world is over populated having kids, etc. 
 
In fact, we are fundamentally irrational, even the best of us. I know from personal experience that my most fundamental desires, the things that motivate my behavior, are often not predicated on rationality or consistency with my belief system. All that pretty much went out the window with puberty. 
 
Here you are criticizing a guy for having a bunch of mistresses? Are you kidding me? I hold some deeply held beliefs that are not consistent with having a harem, but given the opportunity without consequences, you betcha.