No it would be a waste of time and money.
Legally adultery is not against the law! Therefore providing a service that allows people to participate in (legal activities) can't be illegal. Morals vary from person to person. Bigamy (is) against the law.
Some people would never choose to cheat on their spouse no matter how many cheating dating websites were created! Just as not everyone chooses to smoke cigarettes or drink alcohol even though it's legal. The betrayed spouse's issues are with their mate.
Advanced Surveillance Group conducted a study which revealed the (workplace) has become the #1 place for married people who engage in infidelity to meet the other person.
They sited the unavoidable closeness, commonalities in life and the amount of time together can lead to friendship. They end up spending a great deal of time, on occasion more time than they spend at home, with this new “friend” so the friendship can become very deep.
These "friendships" can quickly lead to strong emotional attachments. Strong emotional attachments with the opposite sex can often lead to romance. Beware of the "work spouse" or secret marital confidant.
Surly no betrayed spouse is going to sue the company that hired their wife or husband! Ultimately the (decision to cheat) was made by the spouse. Just because there are online sites, Facebook, nightclubs, strip clubs, and even prostitutes/escorts as available "tools" to accomplish their goal doesn't make them responsible for their mate's decision to cheat. People have always found a way to do so.
If anything I believe these websites help to prevent people from "unknowingly" getting involved with married men or women!
Traditionally there was a high incidence of men removing their wedding rings and innocent women becoming emotionally attached to them. These sites make it possible to "two likeminded" individuals to get together.