1. A system for providing contextual media tagging for selective media exposure with the aid of a digital computer, comprising: a non-transitory computer readable storage medium comprising program code and further comprising: a database configured to maintain a media file; and a set of transformation rules for a user semantic graph; a computer processor and memory with the computer processor coupled to the storage medium, wherein the computer processor is configured to execute the program code to perform steps to: generate with the computer processor contextual information for and collect with the computer processor contextual data regarding a user; associate with the computer processor the media file with the user contextual information; identify with the computer processor insights of the contextual data of the user; generate with the computer processor a semantic graph for the user with the user contextual information comprising a plurality of nodes and edges that create graph structures; match with the computer processor each transformation rule with each graph structure of the user semantic graph; transform with the computer processor the matched graph structure into a single node in the user semantic graph; and share with the computer processor the media file to other computer processors of individuals who belong to a social network of the user over a network to which the computer processor is connected to the other computer processors based on the user contextual information in the user semantic graph.