Spoiler (click to show/hide):
She remains silent seeming a bit sullen as you brush off her words going to practically molest her friend right in front of her even if she couldn't see every way in which you were feeling up Cathy. Cathy trembles as your hands come down on her and your crotch grinds fervently against her plush rear. You can see her lip shake a little as she fights against a moan right there in front of her home. It's dark, but you have to wonder if any of the neighbors might just happen to see the three of you.
"W-we should at least get inside first." Her voice is shaky, and she's clearly having trouble keeping on her feet leaving you to support her body, so she doesn't fall over. She bites her lip when you mention having her friend prep her for you though making it clear you would decide when, or if, she might have the chance to return the favor.