He's tackled everything from angry aliens to rowdy robots with aplomb, but there's one thing that still makes Will Smith uneasy: Love scenes.

"My grandmother was really firm about how men are supposed to treat women," the actor said Friday at a press junket for his new drama Seven Pounds. "So for me, my worst nightmare is for an actress to ... feel like I'm taking this opportunity to get a little quickie feel – you know, some legal cheating going on!"

"I just need, specifically women, to feel comfortable around me," he added. "I just don't want to feel like I'm that dude."

But when Smith's shyness threatened to spill into his romantic moments with Seven Pounds costar Rosario Dawson, his wife Jada had to step in.

"Jada said, 'Listen, I know you're uncomfortable, but you better not embarrass me,' " he said with a laugh. "She said, 'When you do that love scene, you better show 'em what you're working with!' "

Something else Smith is working on: Getting used to all the attention paid to his eleven-year marriage.

"I was with [rapper] Redman the other day [and] he said, 'Man, listen. I've got this relationship that I'm trying to make work, but I'm telling you, if you and Jada don't work, I'm done,' " Smith said.

"That so terrifies me that there are people's lives that I can affect like that just with little stuff, not even having to do anything big," he continued. "So I don't want to break that ... I might mess something up, and that sorta keeps me in a place where I'm really focused and paying attention, and I just don't want to step wrongly."