I understand you’re implying that the girlfriend felated the dealer, and the dealer liked it and gave her extra weed in exchange. But I think we should recognise other possibilities.
Maybe the girlfriend and the drug dealer go wayyyyy back. Like if they were both singing in the same quire or taking bassoon lessons from the same teacher. And the drug dealer was happy to see the girlfriend and gave her the extra weed a gift.
Or maybe the drug dealer is actually a disgraced gynaecologist who treated the girlfriend as a patient many years before he succumbed to alcoholism and was forced to make ends meet by selling weed. And the drug dealer remembered the girlfriend’s symmetrical vulva and perfect areola-to-nipples ratio. And the memory moved him so much that he gave her the extra weed as a gift.
It’s also possible that the girlfriend works for the DEA and instead of burning the weed she confiscates she sells it on the dark web or stacks it at home so that she can surprise her boyfriend with a gift.
It’s also not entirely outside the realm of possibilities that the dealer fucked the girlfriend and was so overwhelmed by the spiritual encounter with her coitoris that he decided to give her a gift.