Romance rumours have swirled around the pair for a while, and now aerial photographs taken of Sean's Malibu home reveal that babyproofing measures have been undertaken.
Snaps of the Oscar-winning actor's luxury home show that a new fence has been installed around the swimming pool and a trampoline has been placed in the back yard – measures that clearly point to prepping for the presence of a little one.
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Charlize and her two-year-old son Jackson have been spending lots of time with Sean lately, with the trio being spotted repeatedly together over recent months.
The Oscar-winning pair appeared to be more than just friends when they rang in the New Year together in Hawaii and were photographed sharing a kiss on the beach near Sean's holiday home.
Into The Wild star Sean showed off his surfing skills in the waves while the Prometheus actress went for a dip and worked on her tan.
The pair, who have been romantically linked several times in the past, have been inseparable since and were pictured together at a post-Oscars party in LA earlier this month.
A source told E! News that the handsome couple "are spending night after night together and moving very fast. It seems like it's getting serious and that they can't get enough of each other."
Another source said: "Sean is head over heels in love with Charlize, and her son Jackson. "He is a totally different person around Charlize, she brings out the gentle and fun side that not many people have seen...
"To see this previously surly grown man, romping around Charlize's backyard with Jackson, with a smile on his face would amaze Sean's detractors. Charlize is getting Sean to not take himself too seriously."