AceShowbiz -

Is Alex Rodriguez jealous of Jennifer Lopez's ex-boyfriends? Rumor has it, the former professional baseball player bans the "Ain't Your Mama" hitmaker from talking to her much-younger ex Casper Smart.

According to sources, Alex took issue with the fact that J.Lo kept in contact with Casper and had her cut off communication. "[He] made it very clear that he isn't comfortable with them talking and that it needs to stop," reveals an insider.

The "Shades of Blue" star allegedly feels the same way. The source tells In Touch, "She usually doesn't listen to a man telling her what to do, but she likes that Alex is expressing how he feels and is a little bit jealous."

Previous report claimed J.Lo and Alex were already talking about marriage. "She really wants to marry Alex by the end of the year. She doesn't want to wait because she knows he's her soul mate," a source explained, "Jennifer not only wants to protect her money, she wants to make sure her kids [nine-year-old twins Max and Emme] are taken care of. Alex is always on top of his finances, so a prenup is very important to him, too."