The moon phase soulmate trend is based on the idea that the phase of the moon when you were born (aka your “natal moon phase”) impacts your personality, and subsequently, how compatible you are with other people. For two people to be “moon phase soulmates,” then, their respective moon phases would be highly compatible.
According to the AstroTwins, your natal moon phase in astrology says a lot about your emotional temperament, which adds another layer of understanding to your moon sign, or your “emotional blueprint.”
And in this moon phase soulmate trend, people are using online apps like CapCut to show what it looks like when they line their natal moon phase up with the natal moon phase of their partner or crush.
Some people doing this trend are working under the assumption that the moon should look full when you line up both people’s moon phases (i.e., a waxing crescent and a waning gibbous, or a first quarter and last quarter moon), while others think you should have the same moon phase. In some cases, others believe moon phase compatibility is more about a balance of differences, like yin and yang, and less about how they look when you line them up.
Ultimately, much of what makes two moon phases compatible comes down to interpretation, though this trend does offer us another way to understand ourselves and think about compatibility.