Even if you have a saintly spouse who wouldn't dream of divorce-raping her (cheating ass of a) husband, splitting financial assets can be BRUTAL. There are, for instance, tax implications. Your investments may appreciate in value over the years, but you aren't taxed on those capital gains until you sell. And if you have to sell a lot of stock in the same tax year (for instance, to wrap up a divorce) you may be hit HARD! Doubly so if you're paying penalties for cashing out an IRA or 401(k) early.

If Mr. Carla can put off the asset division until retirement, when his income likely will be lower, he can realize significant savings. If he manages to live longer than Carla, even better yet! (BTW, that cuts both ways ... if he dies suddenly, pre-divorce, Carla stands a chance of making out like a bandit, especially if he hasn't taken steps to protect his girlfriend, such as drawing up a new will.)

So, yeah ... this is most likely a "cheaper to keep her" scenario. It would be interesting to see the outcome of Carla demanding more intimacy, and whether her estranged husband will feel compelled to slip her the D to maintain the status quo. If so, he'd be rather like the wives of old who were obliged to put out occasionally in order to keep their meal ticket around. We've come a long way, baby! :-D