There is trouble brewing in paradise for April (Rochelle Aytes) and rocker boyfriend Marc (Rob Mayes) in the upcoming episode of "Mistresses."

In the episode titled "Blurred Lines," TV Guide reports that somebody from the singer's past will return to cause trouble. Lately, Marc and April have been enjoying their relationship. Everything seems to be going right for the businesswoman. She is in demand as a personal stylist and her love life is great. In the upcoming episode, she will see both of those achievements crumbling in front of her eyes.

The promo shows Marc being reunited with his ex-girlfriend (Hilty Bowen). While out on a gig, he will be surprised to see the singer in the same room with him. Their chemistry is undeniable as they are shown belting out a powerful song and enjoying it. In the audience, April sees the entire thing and demands to know who is the girl playing sweet music with her man. Later on, the same woman will follow Marc to their place and will ask him for another chance. What will he do?

Although April is happy with her new client Michael (Ian Harvie), she cannot help but be wary of his true motives. He will reportedly overstep his boundaries with the entrepreneur and he will not get away from it unscathed. April is very much in love with Marc, although there is no telling what will happen when her jealousy for his ex-girlfriend kicks in. Will she use Michael as payback for him being nice to the other girl?

Meanwhile, Karen (Yunjin Kim) and Robert (Jerry O'Connell) are doing great in their relationship ever since she dumped him as her daughter's nanny. She decided that she wants him to be around her all the time and took a chance with him. The synopsis reveals, however, that her work will keep her so busy that she will not have much time for her love life. Will their affair fizzle out so soon?

"Mistresses" season 4 airs every Monday at 10 p.m. EST on ABC.