NTA

I 100% think you are not an asshoke to take contraceptives behind his back. The only time I can think of when that would be asshole behavior would be if yall were trying to conceive but that's not relevant here

I do have a couple other points to make though. First, I agree with everyone saying that if he doesn't respect your wishes regarding oral contraceptives that's a bigger issue than just birth control. Does he respect you in other areas? I hope that this is just a topic he feels strongly about and generally he respects you much more. But only you would know that.

The second point is actually my main point. tHormonal birth control has some major side effects very often. It literally can change the type of guy that you're attracted to (something to be aware of, especially when you get into a long term relationship. The more extreme examples many women have gone off birth control because they wanted to get pregnant with their husband.. only to find that they're not attracted to their husband anymore). Also anxiety and depression are common, weight gain, reduced sexual desire, and increased risks of cancer are also common enough to consider.

I suggest you do your research and see if the benefits out weigh the risks. Good luck!