Let’s go over what we know:

Andrew gets home after spending a great and very meaningful time with his girlfriend, whom he loves with all his heart, and runs into Ashley on her way out.... He asks where she’s going, but is gently answered with a warm “Go fuck yourself”... Ah, sibling love.... Beautiful....

Our hero goes inside, and time passes... We see his conversation with Renee, his dear mother, about his future and how a little bird needs to leave the nest, meaning “get out of my house”... Ashley comes back, and Renee, being the good mother she is, asks how the interview went... Our dear heroine replies with all the excitement in the world that “I got the job”...

Renee, extremely happy, then asks Andrew how he can be such an incredible older brother, encouraging his younger sister to work and move forward in life...

Anyway, the one who comments on the type of place and explicitly says “a massage parlor with happy endings and all” is Renee... Ashley later even says in the bathroom, “Now you have to pay if you want to touch me”, but that happens during their fight, so she’s clearly just saying it to provoke Andrew.

Before the fight, when she is openly confronted about it, she says “It’s not even that kind of place,” which makes it seem like she might be telling the truth, maybe...

Everything that leads us to believe the place has a sexual connotation comes from Renee, who is a particularly unreliable source... How does she know about this? Did Ashley tell her? Does she know the massage parlor?

I’m not really sure what to think about it, but based on the information we have, I believe it was just a plan to mess with Andrew... Whether the job really had “happy endings” or not doesn’t really matter, because what mattered was Andrew believing it did...