The pair began dating in 2010 but split up in January, with Ronaldo explaining that he and the Russian model had mutually agreed that a parting of the ways was best for both parties.
"I feel positive and strong," the 29-year-old said of the break-up in an interview with the Spanish edition of Hello magazine. "If you're in a relationship, it should be good. Otherwise, it's best to leave.
"Relationships are hard so one has to be clear about what kind of man you want beside you and what your values are; what is important in your life.
"If you stay with someone, one must walk in the same direction and look at things the same. Both must share the same concept of what a relationship means and both must believe in a monogamous relationship.
"I want a faithful, honest man; a gentleman who knows how to respect women. I do not believe in men that make us fall and be unhappy. That is not the behaviour of a man, but a child.
"I thought that I had the perfect man, but no... I think a woman feels ugly when she has the wrong man. I felt ugly and insecure beside him."
Ronaldo's form and demeanour since his split with Shayk have been the subject of much debate, with the forward having struggled to maintain his remarkable rate of goalscoring from the start of the season, while the 30-year-old announced on Wednesday that he will not be speaking to the press for the rest of the 2014-15 campaign.