My [39 M] relationship with my [38 F] wife has been amazing, the last 3 weeks have been confusing

I have a amazing wife of 20 years, and we have 2 kids in their early 20s. We met in college, and everything has been great between us. Good communication, intimacy, romance, respect, and pretty much everything. <br><br>In the last 3 weeks, we have been distant and not speaking. It started with a phone call I had with an ex. We were discussing our kids, and old times, the conversation was innocent enough. My wife answered the phone, and the ex said "I'll talk to you later" and hung up. My wife has been cold since. When I asked her if everything is fine, she has said yes, and has continued to be cold. I’ve tried to bring her out of her shell with romance, but she has continued to be cold and distant. <br><br>This has continued for 3 weeks. I’ve given her space, as well as attempted to bring her out of her shell with romance, but she has continued to be cold. She has been a great wife, and mother, and we have been a great couple. I am so confused by her actions, and don’t know what to do going forward. <br><br>How can I get things back to normal between us?