The Ex Factor (Harlequin Blaze #569)
Nancy Warren

Wedding planner Karen Petersham loves weddings --- usually. Her newest client, Sophy, has brought along her best man for advice. And the best man is none other than Karen's sexy ex-husband, Dexter Crane. But there are rules when engaging in ex-sex:
1) Do not get romantically involved (obviously)
2) All fun. No fight.
3) Two words --- booty call!
4) (Reminder: nix the romantic involvement)
5) Remember why it ended (important!)
6) And get out before you fall in love with him again ...