She's really holding out hope this romance goes the distance.

We caught Ben Affleck's Playboy model girlfriend Shauna Sexton leaving a medical building yesterday in LA, and when we asked her if she was eager for the actor to get out of rehab, she flashed us a huge smile!

The pinup has been waiting patiently while the Oscar winner gets treatment for alcoholism, and we kind of assumed this budding relationship was dunzo after Jen Garner's intervention, but apparently not.

A source tells X17:
    "Shauna is desperate to keep it going. She's obviously starstruck by him, and thinks he's the sexiest guy ever. Ben has been reassuring her about his feelings via texts from rehab, so she's optimistic that it's more than a fling. Ben's camp would rather he be single and focus on his sobriety, but nobody can tell him what to do when it comes to Shauna. It's more lust than love on his end, but he doesn't want to stop seeing her."

This morning, we caught Ben and Jen going about their business in their Pacific Palisades neighborhood, with Ben being chauffeured to his house by a rehab counselor and Jen grabbing coffee.

We're dying to know what Jen G thinks of all this!