The question of "should we marry" is very complex and goes way beyond simply knowing sun signs. However, I can make some Astro observations. Virgo tendency is to approach issues with innocence and naivete which gives them a sense of clarity. A female Virgo can see the Gemini charm, especially with affection and warmth, in a very accepting and open way.
After 3 years, I would guess that there is a depth of knowledge that you both have about one another that is strong. Ask yourselves these questions: How do we deal with criticism in each other. Has temper come up in conversation. Geminis can be too clever at times. Does he listen well? I have been married for 40 years. If marriage is an issue now, talk about it in terms of goals, plans, and finance. And a big question is about love. Short term is probably not an issue. You both should talk about "long term concerns"