I dont remember Dale forcing sexual favors on Andrea she loved Dale.
Again they never showed it in panel but it was written in text sometime later that that was one of the ways the two girls got Dale to agree to let them stay with him.
i dont think she ever said that they gave him sexual favours to stay in the rv, but they did flirt. i thought it was after he died, back when she was talking to his hat. but i skimmd through, and i didnt see it. im thinking maybe it was after he got bit the first time, but im not sure.
Issue 5. Rick, Shane , and Dale are gathering wood. Rick begins by talking about how Lori tells him about Donna complaining about Dale and the girls. Rick later says Dale earned the right to have two pretty young women to keep him company, because of his camping gear and shower.
Dale: "C'mon, guys... I'm not doing anything with those girls. To be honest, my plumbing ain't what it used to be." (He continues about losing his wife ahd how the girls keep the place clean and remind him of how it was like with his wife)
Issue 64, Rick tries to comfort Andrea and she explains the beginning of her relationship with Dale.
Andrea: "At first, it wasn't anything serious. Amy and I were taking advantage, frankly. Flirt with the old man, get to sleep in the big safe RV. It was a survival thing. Neither of us were actually attracted to him." (The rest of dialogue is about how he offered care and protection to Andrea after her loss of Amy, and falling in love with him and such)
Dale didn't do any "sexual favors" at all between him and the sisters. They just flirted and were nice to him so they could sleep in his RV, but never did they sleep with him. It wasn't until Andrea was really attracted to him after Amy's death that he found another woman to bone after his wife's death.