There are a few astrological signs that are considered very romantically compatible with Gemini, according to Compatible Astrology. These include Aries, Leo, Libra and Aquarius. The astrological signs that are the least compatible with Gemini are Virgo and Pisces.
Each combination of astrological signs has a different level of compatibility. Even strong astrological matches can have relationship issues, and weak astrological matches can end in positive and healthy romantic relationships.
The positions of the moon, sun and planets at the time of each partner's birth are also involved in determining a couple's compatibility. The position of the moon and the ruling planets at the time of birth can have a greater effect on a person's disposition than the sun sign.