A source said: "Britney and Sam are truly happy together but he doesn't want to rush marriage. He wants the best for her and they're just enjoying their time together. Sam loves her and so does his family."

Britney - who has sons Sean, 14, and Jayden, 13, with her ex-husband Kevin Federline - celebrated her 38th birthday on Monday (02.12.19), and the source added she is "doing incredibly well", and is in a "very stable place at the moment" following her stint in a health facility in April this year.

The insider told 'Entertainment Tonight': "Britney struggles to keep her life on track, but right now she's been doing incredibly well. Her family is very proud of the steps she's taken to get where she is today. Britney's been following her doctor's orders and is in a very stable place at the moment. She is trying to keep life simple and spend time with Sam and her kids whenever possible. She plans to spend her birthday with her boys. She wants to just have a nice time with family."

And although Sam isn't rushing into marrying Britney, the actor - who met the blonde beauty whilst shooting the music video for her single 'Slumber Party' - did recently admit he "absolutely" sees wedding bells in their future.

When asked about marrying Britney, he said: "Absolutely. This is something that every couple should do. That's the whole point of a relationship - we are a family."