From the Telegraph interview:
"They [Sarandon and actor Tim Robbins] never considered marriage. 'I've always liked the idea of choosing to be with somebody,' says Sarandon, who has two sons, Jack and Miles, with Robbins, as well as an older daughter, Eva, 25, from a previous relationship with the director Franco Amurri.
"'I thought that if you didn't get married you wouldn't take each other for granted as easily. I don't know if after twentysomething years that was still true.'
"She implies that her relationship with Robbins ran its course. 'You bring people into your life at certain times. Maybe you have a relationship to have children and you realise that it's fulfilled after that point.'
"These days she does not take anything for granted. 'What I've realised in my old age is that your relationship with people or with your job has to be a growing organism,' she says.
"'It's not something where you reach a certain point and then you start preserving it. You have to nurture it, you have to stay curious and hungry and foolish. Once you stop doing that you get satisfied and you get stuck.'"
That's some deep wisdom there, Susan. Reeeeeal deep.