Christina Aguilera Is 'So Happy' About Pregnancy
02/21/2014 AT 05:45 PM EST
"Christina and Matt have been together a long time and always talked about taking the next steps: marriage and growing a family together," the source says. "They've been through a lot and are very close."
Aguilera, 33, who has a 6-year-old son, Max, with ex-husband Jordan Bratman, "really enjoys being a mom," the source adds.
The Voice coach is especially thrilled about giving her son a sibling. "Max has always wanted a little brother or sister," the source says. "That's something really exciting to them – that he will have a playmate. Christina is really close to her sister and Matt has siblings so they are so happy that Max will have the same experience."
Rutler, 29, who met his wife-to-be on the set of her film Burlesque in 2010, is "a natural" with Max and will be a great parent, the source says. "He is wonderful with children. He's not nervous. He really loves Max but he respects that Jordan is Max's dad, so it's exciting to be able to have a full dad role."
So far, her growing baby bump has yet to slow her down. She'll be heading to Kuala Lumpur for a concert in March and will be performing at this year's New Orleans Jazz & Heritage festival in May.
Reporting by MARY MARGARET