I have a nagging feeling that neither will ever re-marry (other people). I simply cannot see it happening. Andrew and Sarah could both have moved on and had second families by now so either they're still in love with eachother or no one in their right mind will commit to them. It's ironic that Andrew is vaguely the most attractive of the four siblings yet is the only one un-married - he reminds me of Prince Albert of Monaco in someways.
This is funny and I tend to agree. Esp. about Sarah. Tho I'm sure (dare I say it) that P Andrew has his own relationship issues as well. Maybe this is why is seems to be throwing himself into his work; to keep loneliness at bay.