I am posting this because it seems to be contrary to the advice of this subreddit. I've been going out with my girlfriend for almost 4 years now. We've had our ups and downs, but nothing related to cheating. We generally see eachother 3-4 times a week and hang out. Sex used to be much more often at the beginning of our relationship (say for the first year) when we would have sex each time we saw eachother and it was reasonable to do so. Now due to our work schedules and my responsibilities we probably have sex once a week on average.

Now, I remembered a few months ago before her birthday that she had mentioned how she thought a pair of headphones that I had was quite nice. So I remembered this and got her a nice pair for her birthday. I don't make it a habit of getting her gifts, especially not expensive gifts. I would say I get her on average 3 gifts per year (birthday, christmas, etc.). She generally reciprocates and gets me something nice for my birthday and christmas.

When I gave her this gift she went absolutely crazy. She couldn't believe it and was so happy. It wasn't a particularly expensive gift, and she could have bought it for herself. Again, I don't make it a habit to pay for any of her stuff. She's definitely not using me to get things. Because if she was, she has stayed in a relationship for 4 years for a total of less than $1000. Not very worthwhile.

My intentions were to do something nice for her on her birthday. This seems contrary to what I've been told to believe on this subreddit. What am I missing here?

My initial thoughts on this are that if I am an "alpha male" then she may already be attracted to me and the gift is just a byproduct of this. Or maybe she wants me to continue this behaviour? I don't think this is the case because I've been quite consistent with my stance on money throughout our relationship.