Not understanding wifey

So here we are at our honeymoon and we are fighting.

A bit of background, we are both very strong personalities and have our own opinions. A lot of times, I don't say things though because I really don't like arguing with her.

So here we are at our honeymoon in Hawaii, and it is our third day. We finally have a day off from doing scheduled activities and we have a chance to check out the resort's spa. The night before, she wanted to check out a luau without mentioning it before. It was kind of pricey, but whatever, we're in Hawaii. So we get a service list of what is available and go to our room to discuss. I asked her what she wanted to do and she picks something that was an individual thing. I pointed out that it was an individual thing and not a couple's thing, and she said "So?" I get annoyed with that and tell her "Fine, go by yourself then" with some attitude. After that, she obviously gets upset and we argue.

Although that might seem like its kind of a stupid reason for me to throw some attitude, while we were booking the hotel for the honeymoon, we were saying stuff about getting a couple's massage and stuff. She's gone before to spas with her friends without me, and being that its out honeymoon and us discussing it before, was it wrong of me to assume that she would have the courtesy to try to pick a couple's thing?

While arguing, she gets loud while I try to talk calmly. She is getting louder and louder and always just justifying herself and her decisions. I tell her she doesn't discuss anything and she just gets loud when I just want to stop arguing. So me being upset as well, I tell her that she is selfish and rude and give her examples. She gets upset and walks out and sits by the pool.

I know that calling her selfish and rude was a harsh point and anybody would've walked out after being called that. This isn't the only example of her being selfish though so don't take it as me being a sensitive idiot. Any advice?