Eric (Timothy West) will try and woo Eva after she become upset and confides in him about her love life, according to the Daily Star.
Eric will be seen buying Eva an expensive bracelet and hinting that he wants to sleep with her in scenes which a show insider said would leave the Rovers Return barmaid "totally shocked".
The carpet salesman will apparently tell Eva: "Gloria's a stimulating woman, but I don't love her. I'm going to call off the wedding. I want to spend my final years with someone I have a connection with, somebody like you."
The source added: "It's one thing trying to steal her sister's fella, but she's not going to go after her gran's. Gloria will hit the roof when she finds out."
[Eva with mother Stella (Michelle Collins) and grandmother Gloria (Sue Johnston)]
Eric will be introduced when Gloria returns to the cobbles, having fled when she was caught trying to fix a 'Pub of the Year' competition in the Rovers' favour.
The new storyline is due to air in March. Get the Inside Soap magazine on your iPhone or iPad