Can a person become addicted to love? To another person? The answer is yes.
Jane's deepest unmet needs are the key. Whatever Jane was denied as a child (be it safety, connection, praise, etc) becomes a little patch of desert in her soul. If someone comes along and sprinkles rain on that patch, Jane wants more rain. She may want it so much, she is willing to do anything to get it, or tolerate anything to keep it.
Let's say Jane grew up feeling unwanted. Along comes Dick who makes her feel wanted. Dick's loving affirmations and attention become the drug. Jane becomes mentally, emotionally, and physically addicted to his attention. It won't matter if Dick later treats her badly. His image has already been imbedded in the positive reward brain system. She feels desperate at the idea of losing him. As Dick's behavior worsens, causing more pain than pleasure, his image still lights up her reward center. Just as drug users know drugs are bad for them but rationalize the use anyway, Jane rationalizes staying with Dick. She may go to therapy and end her addiction, but her brain retains fond memories of Dick. That's why women return to horrible boyfriends even after they've broken up and moved on. Reward becomes entangled with pain and the cycle repeats.
Jane could also be addicted to falling in love. At no other time of life, other than the birth of a baby, does the brain concoct such a neurochemical high. The sun shines brighter. Food tastes richer. Senses are on high alert. In fact, life is a giant Technicolor dream powered by endorphins. Jane could get hooked on that sensation. Since the high can't last indefinitely, Jane eventually returns to earth. The sun isn't as shiny. Food doesn't taste as rich. Sex isn't quite as exciting. Most couples are happy to rely on the fond memories of that initial high. They do small things to try to keep the flame at least a flicker. At some point, Jane could decide that routine drudgery isn't enough. She wants another fix, perhaps another and another. She keeps switching partners to ride that high, or she breaks up and makes up to trick the endorphins into returning. It makes her partners crazy.
When you use this plot device, it helps to know the mechanics of why Jane behaves in this way, especially if you are writing from her point of view. You won't show her thinking, "Wow, I really need the next fix." You show Jane being excited by Dick. When the excitement fades, Jane thinks, I don't really love him. So she trades Dick in for Ted. She is all excited by Ted, at first. The initial excitement fades with him, too. She may go back to Dick. She may break up and make up with Ted. She may move on to Harry. If you want to show character growth, Jane could come to grips with the fact that the Technicolor dream can't last forever. She embraces commitment and learns to love the one she is with. If she is the antagonist and Dick is the protagonist, Dick resolves to be a little more selective next time by paying attention to his romantic partner's dating history.
An addicted Jane might be a frequent user of dating services to get her next fix. If she turns preying mantis and starts knocking off those who disappoint her, you have a plausible serial killer tale.
Next week, we explore Dick as a New Adult