"He" needs to shut down the grow for at least 2 months... box & store all equipment... store seeds in a discreet place... kill all plants and burn/bury the remains
Then make the decision--- to grow again and NOT tell the GF... or not grow... or grow off-premises.
NEVER tell ANYONE you grow- not even Girlfriends, even if they are gonna share the harvest with you.
It was sweet for her to buy the light-- HOWEVER_ relationships often "go South" then that sweet gesture can then become andugly piece of evidence when she decides to be a typical pissy female and turn his ass in for revenge sake!!
(ok- yeah- I am a Woman- but I do not "buy-in" to most women's behavior-- it is so much unnecessary drama and childish etc...)
AND because SHE bought it and obviously lives at home and is MOST LIKELY under-age.... Mom & Dad are the biggest worry right now...he needs to lay low, don't grow, and be on his best behavior!