Oh, come on, you were wondering about this too. From an NRO interview:
NRO: How did you and Mrs. Warren meet?
Warren: Marylyn and I have been married for 46 years come March 22 of this year. We both attended Pepperdine University, but it wasn't until we graduated that we began to date. I feel like the luckiest man alive to have found Marylyn. We didn't know the first thing about selecting a marriage partner. I often say, only somewhat kiddingly, that all I knew was that I should be taller.
The fact is that so many of our best friends from college have had to suffer the excruciating pain of divorce. Marylyn and I avoided this pain because we had broad based compatibility without even knowing it up front. Others were not nearly so lucky. I got started studying mate selection because I didn't want our three girls to have to rely on the luck that saved our own marriage.