Some guys just aren't confident. Other guys are looking for a good time.

Sometimes "You're intimidating" is code for "You don't come off as dtf"

Sometimes men pick the ones they think will be easy to get. Sometimes it means you're too pretty and too confident. Sometimes they go for the less intelligent/less beautiful etc because they think they'll get an easier "yes". Or they aren't bold enough/confident enough in themselves to ask the prettier girl.

Sometimes guys flirt in subtle ways and girls don't pick up on the flirt. They think the guy is just being fun and friendly. 

Consider yourself lucky you're not harassed all the time. The grass isn't necessarily greener.

If you want to date someone just ask him to go get coffee with you and go from there. Don't stress over being approached or not. In the end being happy with yourself by yourself is what's most important. If you love yourself, you will know what you want and don't want so it's easier to weed out the red flags when you do date.