Just get something that suits her and her lifestyle. Don't get just one big rock but several rocks.
I spent about $1,000 on my wife, to the left, and she loves the ring. She gets more compliments about her ring than others who has a solitaire. The group of rocks makes it shine! I don't know how many carats it is.
She loves the ring even til this day
We've been dating for about 5 years too before we got married