Vanessa currently fears that her relationship with Max (Jake Wood) is in crisis due to his distant behaviour, but she is still unaware that he has been cheating on her with Tanya (Jo Joyner).
Lucker told All About Soap: "She can feel she's losing him, but she doesn't know who to. Every time she talks about the wedding, he's totally uninterested. It's humiliating for her."
Confirming that Vanessa does not suspect Tanya, the actress continued: "If she had any suspicions, she'd be stalking them! Tanya's had dinner with them and they've gone out drinking in the pub. Although they're not pals, Vanessa doesn't see Tanya as a threat and would never dream that she could betray her like that."
EastEnders viewers will also see Vanessa smash up Max's home as the situation reaches its climax later this month.
Lucker said of the dramatic scenes: "Vanessa's in such a fragile place. She's in the process of having a breakdown and she's losing control."
Yesterday, it emerged that Vanessa is to find herself at the centre of Michael Moon's schemes in a future plot when he asks for her help in getting revenge against his dad Eddie.
Vanessa will depart screens in the autumn but EastEnders bosses are leaving the door open for her return.
> Read more EastEnders spoilers and news
Watch some of Vanessa's EastEnders best bits in the video below: