The controversial couple still shares an apartment in Washington, a source tells PEOPLE

Mary Kay Letourneau and Vili Fualaau are still living together months after he filed for legal separation following more than a decade of marriage, a source close to Letourneau tells PEOPLE.

“It’s really complicated,” the source says. “There are financial considerations that have made this whole thing a challenge. They’re really trying to go about this as responsibly as possible.”

“I know it sounds awkward,” the source continues, “but they’re figuring it out. It takes a lot of planning to separate after being together for 20 years.”

A source previously told PEOPLE that a reconciliation seemed unlikely.

“They’ve been having issues for a while now,” the source said after the separation filing became public. “They tried to work through them, but it didn’t work. They’re still committed to being good parents to their children.”

Word of the unconventional living arrangement is just the latest development in an illicit, headline-grabbing romantic relationship that dates back to 1996 — when Letourneau was Fualauu’s sixth-grade teacher.

Then in her mid-30s, Letourneau began having sex with Fualaau when he was 12 years old. Their affair ignited national controversy and revulsion, particularly after Letourneau defied a court order to stay away from Fualaau.

After receiving a relatively light sentence for child rape, she was unable to stay away from him and was re-arrested when she was caught having sex with him, again, in a car.

Letourneau was sent back to prison and was released in 2004. She twice became pregnant with Fualaau’s child before he was 15.

ABC News & Barbara Walters 20/20 Exclusive: Mark Kay Letourneau Fualaau and Vili Fualaau on Their 10th Anniversary
Vili Fualaau and Mary Kay Letourneau in 2015
| Credit: Heidi Gutman/ABC/Getty

After finishing her sentence, Letourneau and Fualaau married in 2005 and settled down in King County, Washington — occasionally speaking out about their lives, but maintaining relatively low profiles.

They now live in an apartment in Des Moines, Washington. He has worked at a home improvement store and as a DJ; she has worked a legal assistant.

Their daughters, Audrey and Georgia, are now in college.

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“It’s so hard to explain,” says the source close to Letourneau. “There is a lot history between them, and they’ll always love each other on some level. But this is a weird period for them both.”

Despite the separation, those who know Fualaau and Letourneau say that their connection will endure.

“This developed into something deep,” says family friend Anne Bremner. “They went through this gauntlet of celebrity and scandal. I give them a lot of credit. They will always have a bond.”

Fualaau and his attorney did not return PEOPLE’s requests for comment.