Well, time does change people, so who knows, that could be true. On the other hand, it is hard to know how things are going to feel for her once she's actually back with him.
Not saying this is bad advice but human relationships are way more complex than this. It obviously has worked in your situation but I am not sure it would work for everyone - all depends on the nuances of the people involved, what they need, and whether they recognize what they themselves really need long-term.
I mean, insert two different women into the same situation and one might leave you because you tried too hard to control and manipulate the situation, another might leave you because you never exerted any control, set any boundaries and she lost respect for you / felt you must not desire her as much as the other lover.
Reverse situation but I fell out of love with my ex-girlfriend of 8 years, my first really long-term relationship, because she basically let me do whatever I wanted and I just kind of lost respect for her and she became very predictable and boring. In retrospect, I should have appreciated her more but I was not able to at that time and I don't even know if I could now - sometimes you feel what you feel, despite the brain knowing its probably not fair.
My current wife is more like me and we had a kind of turbulent relationship early on due to two dominant personalities... but we came to understand and respect one another. We are both a little controlling and we have boundaries for one another and it works and it keeps things interesting / we continue to have mutual respect.
I think also there is definitely a balance between some "freedom / not being overly controlling" and a person just doing anything they please in a relationship with no regard for the other. This is especially the case if it involves stuff like telling the husband to be home at X time, then telling him to keep staying out later? I mean, sorry but that is going to get old real fast. Ultimately, there is always a point where total freedom for one person infringes upon the freedom of another to live and enjoy their own life in a reasonable way... but that's another thing you need to sort out for yourself and decide what you can / want to live with. Unless you're happy being totally walked all over (which I guess some where are) then there do need to be some boundaries. If the other person doesn't respect reasonable limitations, then are you being controlling, or are they just being an asshole? lol