Quick Definition: The management of multiple sexual relationships with different women at the same time.
This is a terminology and seduction method, or lifestyle. PUAs are often able to have multiple polyamorous sexual relationships over time. This is opposed to a succession of ONSs with different girls.
The PUA’s understanding of MLTR dives deep into Harem Management and Relationship Management aspects of game. When a PUA has enough value, not just in PU but in other areas of his life, he is able to attract and keep multiple HBs.
Generally, the consensus among the community is that honesty among the polyamorous relationship is the best way to manage it in the long run. Although, some PUAs do keep separate HBs unaware of each other, this applies especially to LDRs and FBs.
Eric managing his GF after sleeping with a Perfect 10 model:
I have 4 MLTRs right now. It is starting to eat into my work schedule.
Source: Fast Seduction