My husband wants me to wear a yellow gown on his birthday but I don't like the color. How do I handle this situation?

As I can make out from your question, that you do not like yellow color, not because you found out that it does not suit you, but because you 'think' it will not suit you. This preconceived notion of yours does not let you wear yellow even if the color, might not look that bad on you.

So before judging baselessly try to give it a shot. Try any yellow colored garment. This will help you in deciding which shade of yellow suits you more. Suppose, you try all the shades of yellow and you find out that 'mustard ' shade suits you the best among all yellows. Then, you can purchase a gown of mustard shade from the market for the birthday party.

If really no shade of yellow looks good on you, you can politely and tactfully convince your husband for some other shades of colors, which will keep both of you happy. You can also use yellow lacer yellow embroidered dress, such that there is a bit of yellow tinge in the dress, of a different color.

So, here too either you wear yellow, intelligently by not looking like a mustard field, but some yellow dress with a contrasting color or you convince your husband for some alternative color which is also his choice. If you make your own choices, he will feel insulted. Try to arrive at a common solution, for his birthday.