Why do men cheat on Halle Berry? Why do men cheat when they can get laid right at home? Cheating and sex are not synonyms. If it were, then having sex with the most beautiful women in the world or having sex 5 times a day would suffice. (I don't want to pass over the 3-4 times a day thing you mention, I'll get back to it).

People derive a lot of things from sex, and sometimes it's important to make sure it's not being used recklessly. In other words sometimes sex can be used as some sort of catch all remedy -- curing them (momentarily) of deep discomfort.

Sometimes, like in the case of rampant cheaters or sex addicts, their sex life amounts to a bucket with holes. They carry it around desperately trying to fill it with things that can pacify their inner turmoil. But, there is no amount of new sex or frequency of sex that can make some people feel at peace , loved, accepted, safe, attractive, desired, complete, etc. Not without working on those issues directly and in ways that doesn't involve their butts or boobs.
 
Now back to 3-4 times a day. I know people have all sorts of libido ranges, but I find it hard to believe that you and your man can sustain day after day sex, 3-4 times a day. When does your vagina nap? When does his wang take a shower? I'm thinking that that sort of sex schedule already speaks to issues that need exploration. The cheating is just another bucket. A bucket filled with holes.