Even though her son is still around, the widow in "The Widow's Lament in Springtime" is all alone. She has lost her husband of thirty-five years. And with that, her strong connection to the natural world seems to have disappeared, too. Anything and everything that once brought her joy has up and left her. Dear widow, Shmoop recommends belting out a little Eric Carmen to ease the pain.
Our speaker's unwillingness to face the loss of her husband (as seen in her avoidance of the issue in the poem) has forced her into isolation from the world.
The natural world isolates our speaker because she now views it in a different way than anyone else views it.