Jessica Simpson and fiance Eric Johnson will sign a prenuptial agreement. The couple - who announced their engagement in November after just six months of dating - have been discussing their options and will agree to a legal deal over their assets before they tie the knot. A source said: "There will definitely be a prenup. Jessica has said she wants one. Jessica and Eric have talked about it. "Eric understands that there needs to be a prenup. He`s supportive of it." Singer-and-actress Jessica is said to be worth $750 million and former NFL star Eric wants to show he`s not after her money. The source added to Us Weekly magazine: "He really loves her. He`s a low-key guy. He`s not into the glitz and materialism of Hollywood at all." While the couple - who have both been married before - are signing a pre-nuptial agreement, they are planning their future together and want to start a family. Jessica said: "I definitely see myself having a family with Eric, so that`s exciting to think about." Speaking about her husband-to-be, the blonde beauty gushed: "Every day is a romantic day with him. I`m very blessed." Jessica was previously married to singer Nick Lachey while Eric`s five-year marriage to wife Keri Johnson was officially ended earlier this year.