Previously, the duration of the marriage played a central role in post-divorce maintenance. Marriages lasting around 10 years, or marriages with children, were generally regarded as having a lasting impact on the spouses' lives. This was a prerequisite for maintenance up to the marital standard of living.
This is no longer entirely the case, as the definition of a marriage with a lasting impact on economic circumstances has changed. The assessment now depends on an overall picture comprising several factors. A common example is where, under a shared life plan, a spouse gave up economic independence, for example by leaving employment to manage the household and care for children, and after a long marriage can no longer return to their previous professional position (BGE 5A_568/2021). The principle that such a marriage almost always entails maintenance has also been abandoned. Maintenance is now payable only where the spouse in need cannot support themselves despite making full use of their earning capacity.
There is therefore no single answer to the question: 'What am I entitled to after 20 years of marriage?' First, consider whether the marriage had a lasting impact on your economic circumstances. This may be the case if you gave up work to care for the household and children and can no longer readily resume your previous career. Next, consider whether you can nevertheless support yourself through employment. If not, you are generally entitled, depending on the other spouse's finances, to post-divorce maintenance up to the standard of living enjoyed during the marriage.
If the answer to the first question is no, the position is different. In a marriage without a lasting impact on economic circumstances you are not entitled to continue enjoying the previous standard of living. Post-divorce maintenance is awarded only if you suffered a marriage-related economic disadvantage. This means you became worse off as a result of marrying. Maintenance is then limited to the amount needed to place you in the position you would have been in had the marriage never taken place. In many cases, no post-divorce maintenance is payable.
In short: The length of the marriage is therefore less important than the division of roles during it. If you wish to make your own arrangements, a marriage contract drawn up during the marriage is one option. In calmer times, you and your partner can agree on maintenance provisions suitable for both parties in the event of divorce. Courts generally uphold such agreements unless their terms are manifestly inappropriate or financial circumstances have changed drastically.