“Should I save his marriage or make him breakup and marry me?”

From a female blog reader:

I guess i should just post it first since its still fresh..i really hope you post this cause i will be reading the comments.
I am a young girl in her early twenties and i recently started seeing this guy who is in his early thirties.Before i met him,i was so desperate to meet someone cause av been single for long.he has been so good to me and even wants to make me fall in love with gim but the issue is that he is married.his marriage isnt working and his wife is unable to give him a child.they always quarrel and argue to the point that i think the best thing for them to do is divorce but the issue is that my friend doesnt want to cause he is so soft hearted but i see him in pain all the time because of his wife but i am always there for him.the truth is deep down i would like it if they divorce so he cn be with me but then on second thought i dont know if theres anything i can do to save his marriage or make him realise that its time to let her go even if he doesnt end up with me. This might be very long but pls am desperate here.any idea will be appreciated,thank you.