I am Cancer, My Lover is Sagittarius
This match is not the best idea. Sagittarius seem so worldly, cultured, and educated, so versed on a wide variety of topics, that it is no wonder you were mesmerized by their sparkling conversation. Your Sagittarius likes to philosophize about such truly important issues in life: Why do bad things happen to good people? Is there such a thing as Fate? Can prejudice really be eradicated? Phew! Sagittarius' job is to ask the hard questions. It is no wonder you are enraptured -- when Sagittarius talk, Cancers will love to listen. But while you are spiritual and intuitive, Sagittarius are inherently intellectual and analytical. Your lover could dismiss your gut point of view as irrelevant nonsense, even though you know it's not. Sagittarius can also get arrogant and tactless. When you tell them you are hurt, they can retort, "Again?" They may make you feel like a bleeding heart or a nutcase.
In bed you will discover how very different you really are. Your Sagittarius lover is all athletics and recreational fun, while you want to give and receive deeply moving, spiritual and emotional love. You can enjoy your Sagittarius lover, but I don't think you will feel ultimately nourished and cared for.
If you love them nevertheless, it is possible you have certain planets in your chart that are compatible with theirs. They are a mutable sign -- very flexible -- so you might also get your lover to understand your viewpoint in time. Keep trying.