The Edinburgh prop, who has been in or around the Scotland squad for 12 years, ended five days of speculation since it was announced he had made himself unavailable to meet South Africa last weekend for "personal reasons", by announcing his decision yesterday.
"To be honest, the last little while it's been in my head that my hunger and my commitment towards it is going," said the 34-year-old, who won the last of his 65 caps against the All Blacks at Murrayfield last week.
"It's not what it was when I was younger. That's a fact. My priorities have changed. I knew when I was in camp for the New Zealand game, I kind of knew that was it then. I was sitting in the hotel wishing I wasn't. I was missing my family more and more. It was the time to say 'bin it before you go down!' I guess it's hard for people to understand, but I know myself in my head that my commitment is not what it was."
Known universally as Chunk and one of the best-liked and most down-to-earth figures in the sport, Jacobsen made it clear that it is not his love of the sport that has diminished but his preparedness to put up with all that surrounds the Test scene.
"I still want to play rugby, definitely," he maintained. "It's never crossed my mind to totally retire, to stop playing rugby right now. I'm still committed to Edinburgh. However, I'm just not willing to take the extra time away from my family that Scotland needs and deserves. It didn't ever seem like I was doing anything and now it started seeming like the biggest drag in the world and I was thinking I didn't want to do that. It could only be a matter of time before everything started dropping off, including my performances, because I didn't want it as much. I didn't want to do that to the players and the coaches and the fans."
While the past 12 years have been a tough time to be a Scottish international player, there have been some great days which he recalled fondly.
"The first time I ran out at Murrayfield was amazing against the BaaBaas [Barbarians] in 2000. It was a non-cap game, but the place was packed and they had a good team. I don't really remember that much about it," he said.
"My first cap in Canada was a big day as well. It was a strange place to get it, but having waited so long since that game here in 2000 before going on tour (to New Zealand with Scotland that summer) . . . I wouldn't describe it as a relief to get a cap, but you'd wanted it for so long. The other one was the Calcutta Cup in 2008. I'd just wanted to do that my whole life. Australia in '09 at home and South Africa the week after we lost to New Zealand in 2010 . . . those are the games I think I'll remember too."