Term for someone who leaves a relationship after the other person buys them a bunch of stuff
Solution 1:
Consider leech:
a person who clings to another for personal gain, especially without giving anything in return, and usually with the implication or effect of exhausting the other's resources; parasite.
Or(e) colloquially, gold-digger:
a woman who associates with or marries a man chiefly for material gain.
[Merriam-Webster]