She expected me to purchase her items with the gifted money.
It looks like you're the one dating a materialistic girlfriend and not you friend. So you should man up and stop saying my friend's girlfriend.
Ladies want to be loved, cared for and pampered with gifts, especially on an important day like the Valentine's day. However, just as all shoes have different sizes, that's how we all have different financial capacities. If a lady cannot accept or is not satisfied with the gifts and money I can shower her at my level. Then, It's a red flag for me and I'd gladly pack my bag and baggages and run a way, because I'll not steal to impress a lady.
Honestly,its so alarming to hear and see how some ladies place unnecessary demands on their partners without a second thought forgetting that they have a better role to play in their relationship.This is why some guys are scared of going into a relationship these days.If you think you're not living to her expectations,I bet you,I'm so sorry for you because you can live up to anyone's expectations.
If she's to materialistic,have a healthy conversation with her,decide on what you can live with,and what you can'nt,understand her personality,and if she's reasonable,she'll understand.