Check 1 — the elements
Every sign belongs to an element: fire, earth, air or water. Fire and air feed each other, and earth and water support each other — those pairs usually flow. Fire with water, or earth with air, takes more work: the same quality that attracts you can also irritate you. Same-element pairs are easy but can feel too similar.
Check 2 — the moon signs
The sun shows who you are becoming; the moon shows how you feel day to day. Two people can chat easily (sun match) but live together uneasily (moon clash). Comparing moon signs shows the daily texture of a bond — how you each handle stress, food, sleep and silence.
Check 3 — Venus, the love planet
Venus shows what makes you feel loved: words, gifts, time, touch or acts of care. If your Venus is in Aries you love bold directness; in Cancer, gentle care. When two people's Venus signs get along, love feels effortless — and when they don't, simply learning each other's 'love language' fixes half the problem.