The couple has reportedly sent out party invites asking guests to keep February 26 free, but the invite didn't include any further details.
They've been together for eight years and have a two-year-old daughter together, so tying the knot seems to be the next step for these two.
A source told The Mail on Sunday newspaper: “Sacha and Isla are throwing a party. They have asked everyone to come in fancy dress. They haven’t told anyone it’s a wedding but that’s what we all suspect.”
Isla even converted to Judaism last year in order to marry Sacha. She said, “I love religions and find them fascinating and I find Judaism very beautiful. It has enriched my life enormously."
We're keeping our fingers crossed for a wedding!