After celebrating her milestone birthday June 15 in a teeny-tiny black bikini during a beach getaway, the Cougar Town actress had another big reason to celebrate: her engagement to Snow Patrol rocker Johnny McDaid.
"Her friends couldn't be more thrilled for her," Michelle Lovitt, Cox's personal trainer and friend, tells PEOPLE in this week's issue. "We're all over the moon that she found this love with Johnny."
McDaid, a Northern Ireland native, "is soft-spoken and calm," says a source who has spent time with them. "Their relationship is really mellow."
And although McDaid is more reserved than Cox's ex-husband, David Arquette, with whom she has 10-year-old daughter Coco, "They get along, so it's really easy for everyone," a Cox pal says.
Reporting by CHARLOTTE TRIGGS
For more on Courteney's engagement bliss – and how she stays so fit at 50 – pick up this week's issue of PEOPLE