Will son get used to pre-school?

For a year now --over 1/4 of this little boy's life-- he has been very unhappy. Why do you think you have to continue? If your wife lacks confidence so much that she can't interact with her own 3 year old and his environment, then she would benefit from some parenting classes. He needs a mom and dad to love him and spend time with him, playing, singing, baking, reading, learning.