Interesting. This subject has never been brought to my attention before.
Pain inthe groin is an issue for all novice male riders. Part of the secret of being "comfortable" , if riding english, is to choose the riding breeches very carefully - riding breeches are specially cut for horse riding. Tight under pants are also helpful.
What eventually allows a man to sit a saddle is the development of the under thigh muscles and the ability to cushion his weight by taking up some of the downward shocks by transferring the weight into the stirrup irons.
He'll start to use his knees, ankle & the balls of his feet to soften the blow(s). But he has to learn how to do that. Strangely it will be his sub concious brain that sorts the problem out but it will take time.
The ratio of women to men in British riding must be something like 9 to 1 and this could be the real reason why men often don't ride. It is a subject rarely discussed in male company.
Thinking about it now, it could be a reason why men sit differently from women in the saddle. Men don't believe they have a pelvic floor and they certainly would not know where to find it.
Normally the male reason for not riding horses is stated to be the lack of control ie no brakes, no accelerator. The real reason can also be the concept of not wishing to look foolish or vulnerable in front of an accomplished female rider - a male ego problem.
Nearly all of the male regular riders I know have a passion for the companionship of a horse and the thrills of riding, the adrenaline, the fear, the exhuberation become a secondary issue as they get older. I am such a man.
Ladies, you must remember that men will often lie to women - it is a defence mechanism. Your man may not want to admit the real truth of why he doesn't want to ride. And be honest, if he is not 100 percent keen then is it such a good idea to put pressure on him to ride?
Horse riding and ownership is as much a lifestyle as a sport.
I have only rarely be able to convince a man to take up horse riding.
Luckily for me one such man was my brother.
PS I shall follow this thread with interest.