Sinitta - who was signed as a recording artist by Simon at the age of 14 and dated him in the 80s - can't imagine the outspoken star ever tying the knot and claims Simon has told her he isn't willing to wed Terri.
She told Britain's New magazine: "Simon said he never wants to get married - he actually told me that."
Simon - who has been dating TV presenter Terri for almost five years - previously labeled marriage as "a ridiculous contract".
The 48-year-old music mogul said: "Marriage is the most ridiculous contract in the world. It's just crazy. Without any legal advice you sign this binding contract and you are not sure where you are going to be in 10 years' time.
"Marriage is not for me. It just feels really out of date. When you've worked hard for your money, you've got to look after yourself."