"X is related to Y". Here, "related" is a quality that X possesses, and means that there is a direct connection between X and Y. If X and Y are people, than it means that they are members of the same family. If X and Y are objects, it either means that the two objects are used together, or that they both do the same type of action.
"X is relating to Y". Here, "relating" is a verb that means "acting as if related" or "becoming closer to". With people, relating typically means that they are talking to each other and enjoying their time, so that they are becoming friends. Relating is rarely used with objects, and if it is used, will have specialized meanings depending on the specific objects in the sentence.
"X relates to Y". Here, "relate"/"relates" is also a verb, but the meaning is different. If X and Y are people, it means that person X can understand the feelings and emotions of person Y in the current situation, as if they were close friends or family (even if they are not). If X and Y are objects or ideas, "relate" means that the two objects or ideas are used in a similar context.
I apologize on behalf of the English language if this is confusing.