And if it seem evil unto you to serve the LORD, choose you this day whom ye will serve; whether the gods which your fathers served that were on the other side of the flood, or the gods of the Amorites, in whose land ye dwell: but as for me and my house, we will serve the LORD.
-Joshua 24:15, KJV
Faithful spouses, you have choices. You do.
Now, they might be all differing degrees of bad. I call them a “Buffet of Bad Options” for good reason. However, that does not absolve us from making the hard choices or accepting the consequences when we do not.
It might be easier not to divorce a serial adulterer in some cases. This I think is especially so in a church that looks down on divorced people and treats them more as damaged goods than valuable community resources.
Even though not divorcing such an unrepentant cheater might be easier, I would suggest God would rather have someone divorce a serial adulterous spouse than enable that sinful and abusive behavior to continue (e.g. Jeremiah 3:8).
Faithful spouses are in no way responsible for being cheated on. However, faithful spouses fully own their choices in response to such behavior.
Is unrepentant cheating acceptable and tolerable to you or are you willing to bear the cost of divorcing such an individual requiring righteousness in your marriage? The faithful spouse owns toleration of cheating if they choose to stay without requiring repentance.
By staying in such a marriage, the faithful spouse is enabling the cheater by shielding him or her from the proper consequences of his or her actions–namely, divorce and all the fallout that comes with that.
Divorce is not the worst outcome following infidelity. Enabling ongoing cheating, abuse, and unrepentant sin in general is far worse. It has both worldly and spiritually disastrous implications for both parties.