I would disagree with this whole-heartedly. We are actually in the generation where people attempt to get married for love and that alone is unsustainable as a relationship binder.
In history, marriage was a business deal between two families.
This is where the "wait until you get married to get her pregnant" thinking came.
Then it moved to finding a life partner -- generally a stay-at-home wife, have kids and keep a solid family foundation. That's where the traditions of "if you get her pregnant, you have to marry her" started.
Now, it's not about family or kids for some, so if you don't love the person exclusively, they won't marry. So, in some cases, they marry the person they love and that person is a terrible business partner. The love breaks down. Because of this, we have less successful marriages and weaker family structures. Now it is " if you get her pregnant, but don't love her, you don't have to marry her but be a father to your child."
There has to be a balance. You should "love your business partner."
This, once again, comes down to self discipline. If you want a successful business / partnership / marriage, ideally, you would also not want to do anything to ruin that.
Love does not make men lose the desire for extra-marital female sex. Men just have to either accept the fact that they can't get everything they want (can't cheat) or do it anyway and potentially bring down the business.