A “serious man” is not a businessman in a suit... A “serious man” is, first of all, a man who is responsible for his words and fulfills his promises immediately. This is a man whose words do not diverge from actions. "Serious man" is honest with himself and with others. If it is a man-woman relationship, then a “serious man” is honest with women. A serious man is consistent, and does not scatter his attention on a hundred women, each promising a “golden mountain”, collecting more and more phone contacts in wats up, communicating with each a little bit and “about nothing”, and then suddenly it gets lost and disappears... A serious man will focus on two women he liked , choosing one fo life during the short time... A serious man for this ONE woman will make her life better and brighter than she was before him...)
I think that when "middle-aged Russian ladies" write to you, "I'm looking for a serious man," these ladies mean a man like I described... But not a businessman in a jacket... A man is measured by his actions towards a woman. And not with words and with what jacket on him.