I am unable to text my wife but I can call her and she can text me

Since you are able to call her , it sounds as if she may have accidentally blocked your text messages.

Have her try the following steps:

Settings > Messages > Blocked Contacts > If your name or number is listed, swipe Left to unblock it.

If not, please let us know and someone on this user-helping-user forum will assist. It might also be useful to let us know which device(s) you are both using.