His post comes after Peh, 28, and Chinese actor Qi Yuwu announced last week that they are dating.
Her break-up with Tonelli had only been revealed last month when she told local entertainment magazine 8 Days that they had grown apart.
In his Facebook post, the 38-year-old Tonelli said that the past four years with Peh "were some of the best years of my life".
"When I met Joanne she was the first Asian girl I ever dated. I didn't know much about her culture and although we were from two different worlds, we somehow connected. The beauty of her soul and her sense of wonder at the possibilities we could achieve together were qualities I was always searching for in a life partner," he recalled.
While the DJ may have seen something in Peh as "life partner" material, marriage was something that didn't seem to have been on the cards.
Peh was quoted as saying that she struggled with frequent questions from the media about when they would tie the knot, and added that it was a good thing she and Italian-American ended things before giving in to pressure to marry.
Both of them blamed a lack of communication on their troubles, though Tonelli's post hinted at a trace of regret when he noted what they could have done differently.
"We had many firsts in our relationship and those moments I will always cherish. As the years passed, we started to lose the communication that is the foundation for every strong partnership. On hindsight, we could have worked a little harder at developing our understanding for each other," he pointed out.
Peh had said, “I want a lifetime partner who can see me through everything. You may not have the same interests or background but there must be communication – and Bobby and I didn’t have that.”
Tonelli ended his post by saying he wanted nothing "but the best for Joanne and trust she will find the inner happiness she so deserves".
The two first started dating after working together on the set of hugely popular local drama The Little Nyonya, where she played the daughter of a well-to-do Peranakan family and he played a foreign expatriate who marries her cousin.
While Peh seems to have moved on, her former flame is keeping to himself. Tonelli said in a post on Twitter Friday that, for the record, he is not dating anyone.