If you aren't willing to do this for him, you should not be in the relationship. If he is dating while he is still married, he may have difficulty committing.
Talk about these issues and be honest with how you are feeling.
DO NOT DATE DURING DIVORCE AND CERTAINLY DO NOT LIVE WITH A GIRLFRIEND OR BOYFRIEND DURING THE DIVORCE.
If you feel you must date, be as discreet as possible, preferably not allowing anyone to know you are dating.
If you are uncomfortable with any aspect of the relationship, he deserves to know.
Be patient with him throughout the process and lend him an ear.
Listen to him about what went wrong in his marriage and what he expects to be different the next time around.
This might mean that you go on dates in another town or do not go out to many public places.
Accept responsibility for your own decisions, and accept the potentially dramatic consequences of your actions.
While dating can be a challenging and confusing time for anyone, adding a man who is separated, but still married, can make things even more complicated.
Marital fault must either be admitted or proven to be used as a reason for the Court to grant a Divorce prior to one year of separation.
However, for all practical purposes, proving marital fault against a spouse in the litigation process (without an admission) will likely take at least one year if not longer.