I'm far from perfect, honey, and I'm not judging you but surely you can see that the only thing you can feel for this random stranger is the equivalent of a schoolgirl crush because you don't know him - but I'm sure you haven't led such a sheltered life that you don't know his type.
He gives you the eye while you're working, you exchange numbers, you're hoping to get to know him so you invite him for coffee and, before the percolator's done it's stuff, he's wanting you to get your knickers off so he can get to it.
Did he misread your signals, or did you misread his? How many other women does he try to get off with while he prices up spuds?
You've lived with an adulterer and you, more than most, must surely know that you'll get considerably more loyalty and devotion from a pooch than the mystery shopper and others of his ilk.
At the moment you're an accident waiting to happen and, unless you do some work on your self-confidence and your self-esteem, you'll continue to end up in casualty suffering from delusions about tossers like the mystery shopper.
FTR, if you're going to go around falling in love with strange (in more ways than one) men, you should know that a man who only wants to get in your knickers is not a good bet for long-term happiness.
Cultivate your self-respect; you don't give out until you've been wined and dined and they've proved without doubt that they have the ability to treat you as you deserve to be treated - and no way is that 'wham, bam, thank you ma'am' within minutes of meeting.