The Terminator star split from Shriver in May (11), days before he confessed to fathering a lovechild with the couple's maid over a decade ago.
Former newswoman Shriver filed for divorce earlier this month (Jul11), but they proved their break-up has been amicable by showing up for the graduation meal at Italian restaurant Toscana in Brentwood, California.
A source tells X17online.com, "They kept their distance... They were there for the benefit of their son but there was no reconciliation going on. They exchanged a few words cordially though."
The pair, which attended with Patrick, arrived and left separately.