I am also a Taurus woman dating a Sagittarius man.
To me sun signs have little to do with our personal relationships. Oftentimes ones ascendent and moon shows more in their personality than their sun sign, and when it comes to love our Venus signs usually tell whether we may be compatible or not.
In my case, I am Taurus sun, ascendent, AND Venus! My moon is in Pisces. My boyfriend (of 3 years… and still going strong) is Sagittarius sun, but shares a Taurus ascendent and moon in Pisces, with Venus in Capricorn.
So while conventionally one may think Taurus and Sag don’t fit together so well in a romantic relationship, the fact that we share ascendent and moon signs signifies that we have very much in common. Our Venus signs, Taurus and Capricorn, are also highly compatible Earth signs.
Never assume that things couldn’t work based simply on a sun sign. Get a copy of your birth chart and read more into it, you’ll be surprised how accurately your personality is spelled out on paper in front of you. It’s also very useful when determining the success of different types of relationships with others.