Do we believe in signs ?

Signs everywhere and nowhere.
Is there somebody who sees them ? Are they any relevant or they are just coincidental ?
How do we know if they have a purpose or signs are just tricks for the mind?
Short story.

A man and a woman met a long time ago, about a year ago without 3 months. They maintained the relation through internet, letters, sometimes calls and messages till the woman decided to put an end . Doesn't matter why, too many reasons , none in fact .
Two days ago , he posted a song "never forget you -noissette " but at that time , never crossed the woman's mind that it could be about her..till today . She turned on the Tv and a commercial distracted her . It was the same song and for curiousity she wanted to know what is all about  and for her surprise was a Nescafe 3 in 1 commercial . She smiled . I forgot to mention that both have a thing with 3 in 1 (actually 3 in 2 ) , it's how they met . Does this mean that he misses her and indirectly he wants her to know ? Is it possible that the woman made a mistake and the signs are telling her to get back in the game ?

Could it be just a coincidence or was that a sign?

After : C-O-I-N-C-I-D-E-N-C-E and nothing else!