keep it as cool as possible, keep changing the water to keep it fresh, add a vase life flower food and trim the ends off every few days. Other than that there is not much else you can do. A florsit may have more idaes so you could try ringing one.
You can dry rose flowers but they shrink, wither and become very delicate to touch and also look very ugly when dry.
Best just to make sure there are some very good photos as memories and get the new husband to buy a new bouquet each anniversary.