Simon Cowell and Lauren Silverman are "each other's rock".
The 'Britain's Got Talent' boss proposed to Lauren, 44, earlier this week, and it's said the loved up couple "bring out the very best" in one another.
An insider told PEOPLE magazine: "They have fun together, as well as being each other's rock.
"They are both passionate [about one another], but really do bring out the very best in each other. As a family, they all have such an incredible bond."
The 62-year-old star has seven-year-old son Eric with Lauren, who has 16-year-old son Adam from a previous relationship.
It's said the couple decided to get engaged after seeing how the world has changed during the COVID-19 pandemic.
The source added: "A lot of things have happened in the last few years and just like for everyone else in the world, these things have all been a reminder about what is precious to them."
Simon is said to have proposed to his partner on a recent family holiday in Barbados, and his friend Amanda Holden - who appears alongside him as a judge on 'BGT' - hopes the couple return to the island for their wedding.
She said: "I would love to think [the wedding would be this year].
"I’m literally messaging them as we speak going, 'Do I need to book flights to Barbados because I want to get in before the prices go up, let me know'...
"Also I’ve got to book time off work, I’ve got to get a hat. I’m thinking, who’s going to look after the kids? Are the kids invited, now come on! Honestly, they need to think about the guests!"
Meanwhile, the TV star admitted she was "shocked" by the announcement as she didn't expect him to ever pop the question.
She explained: "I have to say, I’m probably as shocked as Lauren!
"Simon said he would never get married, and obviously Lauren has been by his side and you now they’ve been through so much together, and I think she’s the one, but I don’t know if she ever thought he would put a ring on it!
"Whilst Simon never thought he was the marrying type, he’s realised he’s met the woman of his dreams - and couldn’t be happier. In the words of Beyoncé, it was time to put a ring on it."