Is NOBODY wrong in the post ? POST : I'll try to explain this the best I can.. I'm not asking for $$ or for relationship advice. My gf currently lives with me. We pay a equal share of rent. She works part time, I work full time so I'm usually the one who pays for things when we go out. Tonight we where supposed to go to a sporting event. Yesterday she expressed she wanted to buy a 150$ Jersey she has always wanted. I thought it was a poor investment considering last month I had to pay a decent amount towards her part of rent because she made some poor financial choices. Money is sort of tight but we aren't going without. Also to mention I'm about to pay a bit of $$ for her birthday weekend coming up and Im buying the tickets to the sporting event(thankfully I hadn't yet). I thought long and hard about how I was going to approach this or if I should at all.. So I pick her up from work and the conversation goes exactly like this.

Her: hey can you take me to (some makeup store) to buy a few things
Me: yes, but do you need it or just want it? (She has more make up than my like 5 gfs combined) 
Her: I want it.
Me: ok that's fine but I want to talk to you about tonight
Her: ok what's up.
Me: I dont think it would a good idea to buy the Jersey.
Her: Why not?
Me: it's just a poor investment, 150$ could go to alot of other stuff.
Her: are you telling me what to do?
Me: Yes I am (I never tell her what to do and I love telling her yes)
Her: what if I do it anyways?
Me: we wont go to the game. I will be mad and disappointed 

Next 5 mins on the car ride home she is trying to explain to me that she has always wanted it and she rather not go to the game and instead get her the Jersey.. 

We get home

I kept my voice down I tried not let it turn into a argument but she said "well if I have to move out today then I guess I will". (I never told her she had to move out). I said do what you want and she then tried to switch it around on me by saying "now you want me to move out?" I explained every which way to her that it wasnt a good idea then she told me "maybe you should have approached me differently she had a bad day at work". Was I supposed to beg her not to? And before the car ride conversation I asked her how her day was and she said it was fine. I'm trying to think if I missed any points but that's pretty much it.. but as of now we arent going to the sporting event and she is still mad.

TLDR:My gf is mad because I told her "No" about buying a 150$ sports Jersey.

P.s I had to Google what TLDR ment I always see it at the bottom of stories and figured it was a summary when a story is long.. 