You want Helen to experience it too

"I think you're talking more about your own needs than Marisa's. I will do as you want, but my price is that you let me show you the wonders of being a woman," you say.

"No, not that," Helen says weakly.

"All those time people has been talking about their spouses, all those time you've been going alone, all the questions you can't answers. Don't you want that to be all over?"

"I do, but I'm afraid"

"I'll be as gentle as you need; I just hate watching a beautiful woman as yourself wither away. You need this more than Marisa."

"I don't know, I have tried doing before. I don't know if I can anymore," Helen says and you can feel the despair in her voice.

"I heard you saying that you didn't want Marisa end up an old maid like you. It doesn't have to end that way for you, you're still young and beautiful. Stop thinking about what you got to lose, think about what you can win if this works out. You can win your life back," you say.

"I don't know," Helen says, she is still not convinced.

"I think you should do it mother," you suddenly hear Marisa's voice. Apparently she is done changing her clothes.

"Are you sure?" Helen says, with tears welling up her eyes.

"I'm sure," Marisa walks up to he mother hugging her as she continue to weep.

You feel a bit misplaced, watching the mother and daughter sharing this private moment. Marisa is drying the tears as they continue to drop, comforting her mother with encouraging words until Helen stops crying and speaks up.

"Okay I'll do it, I think I'm ready to try it again," Helen says, still relying on Marisa for support.

"Marisa do you know what Helen was asking me to do?" you ask giving air to your suspicion that she might've been in on it.

"I..." Marisa says and looks at her mother.

"It's okay Marisa," Helen says.

"I knew...I just thought, I didn't...I mean," Marisa is just blabbering nonsense.

"She told me you were coming over and I thought that it would be good idea to try convincing you to sleep with my little daughter, little did I know what kind of mess it would get me into to," Helen says and lets out a small laugh.

Helen and Marisa turn their attention to you.

"I want you to start with my daughter first," Helen says.

Marisa doesn't look like she minds either way, or maybe you could try to steer this into a three-way.