I do think that men need some kind of work, or focus to their life. In the absence of a family, which men don't really have a biological desire to have. (Women often seem to. Men enjoy the trappings, but it seems a socialized thing, rather than biology forcing them to the task. If that was the case, no men would ever cheat or stray, no matter how hard things got.)
This doesn't mean that can't be important or a goal for some men, just that it's a thing they choose or learn, rather than being inborn.
Regardless of where men are however, there is a trend which has the best of them working hard to get things done. I'm actually trying to promote that idea. (For women too, by the way. I do like seeing people doing their best, and being successful because of it.)
I also think that modern marriage, even separated from the new laws, isn't a natural human bonding system. It's an artificial construct designed to help women, and care for their children. (About 1-6 children that a man thinks are his isn't. That's a lot...) historically, there was no real way to tell reliably. Now that there is, things are shaking out to be a lot different than we might have thought even fifty years ago. Men don't need, or even mainly like, marriage. This doesn't mean that it can't be good, but it generally isn't. Women seem to dislike it as well. (Most divorces are asked for by the wife, and the most common reason is general dissatisfaction, rather than having a good reason. And yes, I'm saying that if you sign on to be married, getting bored isn't a good enough reason to dissolve it.)
Given this, I don't really think that men have a biological need that isn't being taken care of if they don't marry or have relationships in particular. this may eventually turnout to be wrong, but so far I think that keeping busy is a part of the male mind, but separate from relationship status. It's just that when you are free from that kind of thing you have more time to do what interests you, instead of carrying for your family and wife first and foremost in all things. (Though if you ARE married, then you should give those things your all. You signed a contract and took a vow. Live it. Do your very best in it.)
Now... I don't even know if that was relevant!