Entering a relationship with a man you know that he is a womanizer is a choice you have to live with no matter the consequences. Women believe in changing a man and that whatever habit that he has, she is capable of changing that to something better. The best way to approach this character it give him as much freedom as possible, while you keep it real and playing hard to get. Men like challenges which means he will drop all that keeps him busy and focus on you, his new project.
A woman is likely to find the man with someone yet not serious with them in most cases. The man wouldn’t just drop the other woman just because of the new comer. He will weigh his options to see who is fitting to be in a relationship with. As long as he uses protection, give him time to deal with his mess while his mind is slowly being shifted to your side. Men are like teenagers and they are more into what interests them without any drama or stress. Be there and make his other lovers non of your business, then he will start dumping them one by one keeping only you.