Saying goodbye to someone you love is never easy, but it can be even harder for rescue dogs β€” for whom "goodbye" often means a ride to the shelter and an uncertain future.

On Sunday, Astra's foster parents returned her to NYC-based Red Hook Dog Rescue (RHDR), and the experience was absolutely devastating.

Astra watched from inside the RHDR volunteer's car as her foster parent walked away after saying goodbye.

Facebook/Red Hook Dog Rescue

A volunteer from RHDR was there to pick up Astra. She photographed the heartbreaking moment Astra said goodbye to her foster. In the caption of the photo, she wrote that for the 2-year-old pit bull mix, "her world has crumbled and her beautiful spirit is crushed."

"As we drove to the vets office where she will be once again boarded, she saw a person that resembled her foster and her tail began to wag until she realized it wasn't her beloved person and she laid down to sulk," she continued.

Facebook/Red Hook Dog Rescue

"I took this photo right after Astra realized she would no longer see her beloved foster," reads the photo's caption.

"We understand it was difficult for the foster," a RHDR volunteer told The Dodo. The family lives on the 18th floor of a rise-up building, and Astra would be fine when encountering 9 out of 10 dogs in the elevator. But on occasion, she couldn't handle the stress of being in such a closed space with a dog who made her uncomfortable.

"We keep in touch with the foster and [are] grateful they have given her a relief from boarding for two months," the volunteer continued. "We, as a rescue, strongly believe in suitability, and they were just not the right family for her."

Looking into Astra's eyes in the above photo, it's difficult to not see the world of hurt and sadness going on inside her heart. Sadly, this recent misfortune is just the latest chapter in Astra's continuing story of finding a forever home.

Although RHDR describes her as a " super mellow" dog who also happens to be the "queen of cuddles and snuggling," Astra has shuffled between three foster homes in the past nine months; when not with a family, she's been boarded at a vet's office.

Here's a video from when RHDR tried to get Astra adopted in snowy February.

Here's a photo of Astra after she left her previous foster in March.

Since RHDR posted the most recent photos of Astra, applications have been pouring in to foster and adopt the sweet dog. But the groups still has many other dogs, such as Sally, who need homes. Sally, below, has been in and out of shelters and foster homes for the past three years.

It's time to get Astra and the other dogs of RHDR into their forever homes. If you or someone you know lives in the NYC area and have a place in your home for a dog in need of a loving human, check out RHDR's adoption application.

If you're committed to providing a temporary home for rescued dogs, check out RHDR's foster application page here.