Jeff Tseguay is a minor character in The Secret Life of the American Teenager, introduced in Season 2. He is the ex-husband of Kathleen Bowman. He is an obstetrician\gynecologist and was the step-father of Grace and Tom Bowman.
He met Kathleen six months after her husband Dr. Marshall Bowman died in a plane crash. Their relationship is discovered inadvertently by Jack while he's at a drug store & notices the two of them buying contraceptives. Jack agrees not to tell Grace about Jeff, but Kathleen ends up telling her anyway.
One evening, Kathleen is at Jeff's house and Jeff decides not to answer a phone call from his mother. His mother becomes concerned and bursts in on the couple talking in bed, much to Jeff's chagrin, Kathleen's embarrassment and his mother's interest.
Jeff and Kathleen's relationship escalates quickly and upon Grace's pretense at encouragement, they decide to marry. The day after the wedding, Jeff talks to Grace and tells her that he feels that they got off on the wrong foot and he invites her to talk about her misgivings. During the talk, Grace begins to sort out her conflicted feelings about sex.
Jeff later joins a medical team working for an extended period in Africa, where Grace visits him and meets Daniel. He invites Kathleen to join him in Africa for a few months. Although tempted, she doesn't feel that she can leave Tom and Grace.
Kathleen later divorces Jeff and goes back to George Juergens.