According to ESPN's Adam Schefter the leave will be to attend to Smith's wife, Tiffany, who was just diagnosed with breast cancer.
31-33 through four seasons, O'Brien wound up at odds with GM Rick Smith throughout the 2017 campaign, but Smith is taking an extended leave of absence, and O'Brien will now head up a search for Smith's replacement. "I remain committed to our quest to bring a championship to the city of Houston, yet my family needs me now and they are my priority".
Houston struggled to a 4-12 finish this season, however, and there are questions regarding whether Smith will be back with the team in 2018. Should McNair decide to punt and put off the decision until O'Brien's contract expires next year, sources say the Texans could be maintaining a hard work environment. However, the most important thing at the moment is the health of Smith's wife.
Smith has been the general manager for the franchise since 2006 and was elevated to an additional role as executive vice president in 2012. It is unlikely the team would allow him to coach next season without signing him to a contract extension in the offseason.
After Sunday's loss to the Colts, O'Brien called his first losing season as an National Football League coach "absolutely brutal".
O'Brien has went 9-7 each of his first 3 years until this season and is in his final year of his contract.