In a divorce with college-aged kids, is there a custody arrangement?

Why would there be a custody arrangement for adult children?  There isn't. there may be an agreement drawn up about the college tuition payment, though.  Most couples who are sane can make agreements about this before the divorce hearing.

No, they are adults.

Once a child has reached the age of 18, unless the courts have deemed them unable to be without a custodial guardian, they are legally held responsible for themselves and there is zero reason for "custody". Adults don't require "custody" and unless the Court has legally declared them unable to be in charge of themselves, "custody", once an adult, will be disregarded and terminated.

No. However there could still be child support or an agreement to help continue to pay for college. To be fair, it's actually really difficult for young adults to find out their parents split. They feel like their whole lives were a lie and that the parents only stayed together for them and waited until they went to school to split up. Make sure both parents have enough space so that the child/ren feel welcome in both places and make it amicable. Your divorce will make it harder for them to ever trust marriage.  And to be fair, it may seem like a great idea to get to live your life freely again, but sometimes all you need to do is to reconnect. At the age where the kids go off to college, menopause is usually happening. There is a sense of "is this all there is?" and wanting to get your life back. Many people think that means starting over with other people. But getting to know yourselves again doesn't mean necessarily splitting. It means finding your own interests and not needing to be connected at the hip. It means not trying to get someone else outside of your marriage to make you feel alive again. It's about finding it within yourselves to feel alive again. If it's over, it's over but it's a common time to quit and leave yourselves financially vulnerable in your gray years and once you see the grass isn't always greener, you lose what you had.

If they are under 18, yes.