Is it permissible to pray for marriage to a married man who is 17 years older than the supplicant, knowing that he refused to marry because he loves his wife and family?

A woman's supplication to marry a specific man is permissible, but it is better for her to turn away from that and supplicate that Allah bless her with a righteous husband. For Allah knows best what is good and righteous, "But perhaps you hate a thing and it is good for you; and perhaps you love a thing and it is bad for you. And Allah Knows, while you know not."