If there were more men like Boaz, then there might be more young women willing to marry them despite the age difference.
At any rate, marrying an older man is not what made Rus a tzadeikes. In fact, most tzidkanyos I have heard of were married to men about their own age, such as Rebbetzin Kanievsky and Rebbetzin Scheinberg – one has nothing to do with the other.
I get the feeling this question is personal. Are you perhaps an older man wishing to marry a young woman?