"My boyfriend robbed me for years, and I never noticed."

When Rachel Rosenthal’s money started disappearing from her bank account, she thought her credit card had been stolen. The reality was much worse.

It took months of moving her money from bank to bank to realise this wasn’t the case – that somehow, inexplicably, someone had accessed the most intimate details of her life and stolen her identity.

Speaking to podcast This American Life on an episode titled “The Perils of Intimacy”, Rachel describes her growing anxiety upon realising the theft was a problem she couldn’t solve.

No matter how many times Rachel switched banks, the thief followed. Money disappeared a little bit at a time, never all at once.

“I started to become a very paranoid person all the time. There was one point where I thought my mail was being stolen… so I got a PO Box,” Rachel told This American Life.

“I was so paranoid I would try to find alternate routes to get to my PO Box… I thought someone was following me.”

The strangest thing was, Rachel wasn't particularly wealthy. She worked at a non-profit organisation for a very modest salary, and couldn't understand why she was being consistently targeted by such a cunning thief.

Luckily, she had a boyfriend who seemed to understand her predicament. He picked up grocery bills and rent when she couldn't. With his job at the Massachusetts State House, he made good money, and was always willing to share.

After moving from bank to bank to no avail, Rachel eventually bit the bullet and withdrew her final $1000 in the form of a bank cheque, which she hid in a drawer in her apartment for safekeeping.

From then on, she paid for everything in cash only, and was paid by her job in money orders.

It was a drastic step, but Rachel believed it would stop the identity theft for good.

She was wrong.

A few months later, when Rachel and her boyfriend decided to move house, she needed $1000 for the move. She went to the drawer to grab the bank cheque.

It wasn't there.

At first, she couldn't believe what had happened. She and her boyfriend tore apart the apartment, desperate to find the cheque - the only money that Rachel had remaining in the world.

When they couldn't, she went to the bank, where they told her they couldn't help her.

She'd already cashed that cheque, they said, and showed her a copy of the receipt.

Rachel recognised the signature immediately. It was a poor forgery of her own, in her boyfriend's handwriting.

It shouldn't have come as a surprise. In fact, when Rachel 's money began disappearing from the banking system, that had been the first thing they'd told her.

"Any bank or police officer would tell me, it's the boyfriend. It's always the boyfriend," Rachel reflects. "And I would say, you don't know my boyfriend."

Her boyfriend wasn't a criminal. In fact, he was the only one who understood how much the whole saga had affected her, increased her anxiety, worn her down. When she was having a bad day, or when she noticed more money missing, it was her boyfriend who made it okay - who told her not to worry about rent that month, or who made her an expensive home-cooked meal to cheer her up.

"My boyfriend is the king of generosity and kindness," Rachel remembers thinking. "Just so giving, all the time."

When Rachel confronted him back at their apartment, he broke down crying.

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"I have to tell you something," he said. "I don't want to tell you, because I'm afraid if I tell you you're going to leave me."

He told her he had "impulse control disorder", a psychiatric disorder characterised by wild impulsivity. He claimed he was seeing a therapist for the behaviour, and Rachel believed him.

"I think I needed to hear that there was some sort of medical reason. 'He's not a bad person, he's just like... going through something that's out of his control.' Not like... 'you've been living for years with a sociopath'."

The strange thing is, Rachel didn't put together the whole picture. She thought her boyfriend's disorder had caused him to steal her cheque, cash it at the bank, forge her signature and then help her look for it like nothing had happened, but she didn't imagine - not even then - that he had been behind the theft from her bank accounts.

Rachel and her boyfriend stayed together for another year and a half.

"It makes me sound so stupid," she reflects, "but I really thought I knew what good was. Everything felt so bad and so hard to control, and I was like, he has to be good. If he's not good, nothing is good."

She rationalised their relationship to herself constantly: "There's no way it's him, because he literally supports me. He buys all our groceries and pays all our bills and is my personal army to figure out the identity fraud. Why would someone steal from you and then spend it on you?"

But the identity theft continued. Soon, she's in debt over credit cards taken out in her name. She's panicked and upset, and occasionally wonders whether it would all stop if she ended the relationship.

One night,  Rachel's boyfriend asks her to marry him. She says yes.

The next morning, she gets a call from her landlord. She'd hardly ever spoken to him, because her boyfriend was in charge of making sure their rent got paid.

"He was just screaming. He said, 'I don't know what you are your boyfriend are trying to pull, but you owe me $16,000. You're being evicted.'"

As it turned out, Rachel had been giving her boyfriend her half of the rent for a year, but none of it had made it to the landlord.

When her boyfriend got home from work, she confronts him, and eventually - after a strange few weeks in which they sporadically planned their wedding - they agree to "take a break for a few days".

Rachel's boyfriend went home to his parents, and she never saw him again.

It was only months later that Rachel finally put all the pieces of the puzzle together: that her boyfriend had been stealing from her for five years. That his job at the State House was fictitious, and that he was only pretending to go to work each day. That the coworkers he spoke of so often didn't exist, and that the various "work trips" he'd taken throughout their relationship were made up too.

"I don't know anything that was real," Rachel says now.

Listen to the full episode of This American Life here.