This is hard to interpret in any meaningful way because you are cherry-picking your Moon sign and his Mercury sign. He has Mercury in Gemini, not Gemini in Mercury. Every planet is in a zodiac sign in every person's chart.
Cancer is an emotional sign but is ruled by the Moon, so you do have positive feelings. They change often. But you are also nurturing, kind, a good listener, romantic, and generally like being in a partnership. Mercury rules the way people think. His in Gemini means he thinks fast, about a lot of topics at one time. It's hard to keep up with him mentally, and he may view romance through an intellectual lens. I don't know where your Mercury is, but writing articles about Mercury in all the zodiac signs on Exemplore.com, and there is a link on all of them where you can find out. It's the same link on all of them, so it's doesn't matter if you get to the right article the first time.
Cancer planets do cause a person to hold things in, and maybe let out so much at once when it all gets overwhelming, it can leave the other person stunned (I have 3 planets in Cancer, and my husband used to beg me to not hold things in and then discuss years worth of issues at once)! So I do get it. I am going to guess you have more than the Moon in Cancer. If you can speak up more often about how you feel, and he can be a bit more understanding, that would help. But this really isn't much for me to compare, and it's like apples to oranges. Try looking up your Mercury sign and his Moon sign, so you can compare the same planets you each have to each other. All my Moon Sign Emotions articles have the same kind of Moon link. Find his Moon, your Mercury, and read the articles. You will find out a lot.