"It's bizarre," the actor told USA Today Wednesday, adding that he avoids looking at photos of Witherspoon and boyfriend Jake Gyllenhaal.
"There's plenty of times when I say, 'What a strange situation I've found myself in,' " he said. "But at a certain point you know it's going to happen, so you are prepared."
Phillippe, 33, split from Witherspoon the mother of his two children, Ava, 8, and Deacon, 4 in October 2006. The actress's new romance first made headlines last March, when she and the Brokeback Mountain star were spotted dining at L.A.'s Il Sole.
As for Phillippe's own love life, the actor who's been linked to actress Abbie Cornish remained reticent. "It's just something I would really rather not address," he told the paper. "It has to be a 'no comment.' "
He also insists that despite a painful divorce, he isn't ruling out a second marriage.
"I can see doing it again, yeah," he said. "And I can certainly see possibly having children again. I'm pretty young, and there are many beautiful things about that idea of marriage and family. It just doesn't always work out perfect for everybody."