Why do some spouses receive "rehabilitative maintenance" for a long period of time?

Rehabilitative maintenance is, for the most part, temporary. In fact, one could say that 99.9% of all rehabilitative maintenance cases are temporary. Having said that, we have to acknowledge that in very distinct cases, with very particular sets of facts, rehabilitative maintenance has been extended for several years, and in a very few cases rehabilitative maintenance has been continued for life. In these cases the recipient ex-spouse had no realistic chance of employment, and the marriage had endured for a substantial number of years.

For example: it would be unrealistic to expect a woman, now in her sixties, who had been married for forty-some years, to be able to find employment that would guarantee her a living standard at the level to which she had become accustomed with her ex-husband.