We are both horse I think he's January 14 1978 and I'm September 10 1978.

The zodiac is based on the lunar calendar. In this case, your boyfriend was born the sixth day of the twelfth lunar month of 1977, the snake year.
It is predicted that the two of you hold several different values and opinons in daily life. The key to keep this relationship is to tolerate the divergences and make some changes for the other one.
If you can manage this small issue well, you are going to have a sweet love life. Good luck!