Long-distance relationship (LDR) or long-distance romantic relationship (LDRR)

A long-distance relationship (LDR) (or long-distance romantic relationship (LDRR) is an intimate relationship between partners who are geographically separated from one another. Partners in LDRs face geographic separation and lack of face-to-face contact. LDRs are particularly prevalent among college students- constituting 25% to 50% of all relationships.[1] Even though scholars have reported a significant number of LDRs in undergraduate populations, long-distance relationships continue to be an understudied phenomenon.

Source: https://en.wikipedia.org/wiki/Long-distance_relationship