Review the item:
Rachel painstakingly ironed her linen shirt all
the while, she was thinking how pointless this chore was since linen begins
to wrinkle the moment after the last button is fastened.
A comma splice occurs when two complete sentences are incorrectly joined with just a comma. In the example above, no such comma exists. Rachel painstakingly ironed her linen shirt is one sentence. All the while, she was thinking … begins the second sentence.
Because only empty space exists between the two, you should call this error a fused sentence.
To fix the problem above, you could put a period after shirt and begin all with a capital A.