Meaning: An attitude towards love where love only means lust. No kind of emotional attachment or connection, just hooking up one after another and it continues until it burns the person out.
This neologism inspired from the word 'Junk Food'—'Junk Food' or 'Junk Love'—both are harmful.
There are those who may be addicted to that love "high." They need that amphetamine-like rush of dopamine, norepinephrine and phenylethylamine. Because the body builds up a tolerance to these chemicals, it begins to take more and more to give love junkies that high. They go through relationship after relationship to get their fix.
(via How Stuff Works)
Someone who NEEDS to be in a relationship as much as an addict NEEDS their crack, heroin, or whatever else. As soon as one relationship starts do go downhill or ends, the love junkie will quickly have someone else lined up so they're not single for longer than a few weeks. They have little to no identity outside whoever they're with, and as quickly as they attached to you, they detach and find their next fix.
My ex was such a love junkie, we got together 2 weeks after she broke up with Tina, and when we started having problems she started romancing her online friend in NC who she left me for at the end.