Grouped elements, arranged in what is interpreted as a pattern, are considered part of a unit. And, as part of that unit their relationship and meaning are perceived as comparable.
Conversely, if items are spread far enough apart, without pattern or any other obvious relationship, they are perceived as separate items, for the user, parsing and understanding these elements is more difficult as each element needs to be considered individually.
The principle of proximity, in user interface design is applied where the designer wishes to demonstrate a relationship, between elements of similar meaning, relationship or value, in relation to the user goal.
Misuse of this principle, whether intentional or not, can occur when objects with no real relationship are grouped by proximity or alignment, mistakenly creating a relationship between the objects.