A bit more information would be helpful before people start giving suggestions which have no bearing on your situation. What phones you have, plan, etc... People just assuming about your situation just wastes time.
Whenever an android cannot receive texts from an iPhone, you have to consider iMessage as the culprit. Whether or not it is, you should always consider it.
What color are the bubbles around the texts she sends to you? If they are blue, her iPhone thinks it is sending the message to another iPhone utilizing iMessage. If they are green, they are being sent as texts and it is unlikely iMessage is not the culprit.
There are multiple reasons why this could have just started. 1 - you recently switched to an android from an iPhone without fully disabling iMessage. 2 - you signed into an Apple userid account on an Apple device other than an iPhone recently and now her phone is sending all of the messages to your contact info via iMessage. There may be other reasons, but those are the 2 which come to mind.
Info about correcting this possible cause can be seen in the following location.
If the bubbles around your wife's messages to you are green, it is probably a different cause and you may have to call CS to remedy the situation.
Is it possible that you have several hundred (or even thousands) of SMS messages from your wife? You may need to delete some of them. I have my SMS program auto-delete when the message thread gets to 250.
This started on April 17. Nothing changed that we are aware of. We are both using the factory text application. She does not get an error and assumed the messages are delivered. She receives my texts without problem.
Sent from my Verizon Wireless 4G LTE smartphone