Oh, agreed. It's an unlikely scenario, but it's still within the realm of possibility. As long as we're speculating on what might happen in regards to the spell, it's fun to think over how it might backfire.
Depending on the exact nature of the suggestion, Jillian wouldn't necessary have to break the spell to act that way. If the spell is centered around Wanda, Jillian may decide that Wanda's game is too dangerous, and save her by personally capturing her and seeing that she gets treated well. It would require that Jillian take the initiative in their relationship, though.