Actually, we don't find out; we find out that my presumption that Connie drove away crying without asking who Allo Girl was is correct.
Panel 1: As we see Connie confronted by Allo Girl, Elly narrates "When Connie knocked on Phil's door, a very pretty girl answered. Connie did not know what to do."
Panel 2: As she holds out the pipe, Elly's voice-over reads "She said that she was just passing through the neighborhood and had come to return his pipe."
Panel 3: We next see Allo Girl smile and beckon a reluctant Connie inside; Elly's voice-over reads "She said that Phil would be back very soon and asked her to come in but she said she had other things to do." This, of course, means "The woman said that Phil would be back very soon and asked her to come in but Connie said she had other things to do."
Panel 4: Annie reminds Elly, who's folding laundry, "But Elly, she'd come there specifically to see him. What else did she have to do?"
Panel 5: I'll tell you what she did; sit in her car and cry because Cheating Cheater Who Cheats Phil Broke Her Heart.
Summary: You and I know that there are a thousand different innocuous reasons for Allo Girl to be there but Lynn can only see the one: Phil is spreading it around because he wants to make a fool of Connie. That's because she's a narrow-minded old fool who can't even see how dumb she looks.