The stubbornness can have a lot to do with it. Aquarius is a fixed sign like Taurus though. And all of the 10 planets are in a zodiac sign in your chart. The Sun, Moon, Ascendant, Mercury, Venus, Mars, Jupiter, Saturn, Uranus, Neptune, and Pluto. So I don't think Sun signs alone carry enough weight to be the cause of divorce for a couple who has been married for 15 yrs.
Now, you could both have several planets in Taurus and Aquarius. This can work in a stubborn way, but also in a persistent one if you both really wanted to work on the marriage. I would have to cast a whole chart to see what's really going on, and I don't do that for free. Taurus and Aquarius are what is called a square aspect in astrology. You both think you are always right. Taurus is more reluctant to change than Aquarius is. Aquarius actually likes change, and is apt to change suddenly and without any warning. They also get bored faster in a relationship. So I would think both parties have some blame here. Squares are not inherently bad, they create a lot of sexual chemistry. I'm sorry that you can't work it out but would need a lot more info. Take care of yourself.