The caption that Michelle included with this photo on Instagram also points to Zahn being Wie's boyfriend:
The only boyfriend we've known about in Wiesy's past was Robin Lopez, the 7-footer who was at Stanford with her and has gone on to a decent NBA career.
Zahn, 32 years old, played his college ball at the University of Oregon. He measures in at 6-foot-8. And while he never achieved an NBA career, he did see the world playing pro basketball. Zahn, who now lives in California, had played professionally in a league in Japan, and even one in Iraq, in addition to spending some time in the D-League.
NBA centers might be the only men in America tall enough for Michelle.
Update I: We can confirm that Michelle and Adam are a couple and have been for a couple years. Back in October of 2014, Adam's mother wrote a comment on a friend's blog, and told the friend, "Adam our middle is dating Michelle Wie – the golfer ... she will be joining us for Christmas this year!"
Update II: Alas, Michelle appears to have deleted that Instagram post. So here's another photo of Michelle and her boyfriend, Adam Zahn: