Mid Life Crisis

I have been on a weird emotional roller-coaster.
Last year I learned that the best man from my wedding, left his wife and 3 kids. His ex wife called me and we commiserated on mid-life crisis men.
Last week I found that he was getting married. I laughed and said to my ex "Already?
Some people never learn"
I have so many emotions about this.
First, sorrow for the feelings of his ex. She was heartbroken over their divorce and didn't see it coming. She's going to be okay. She has a decent job and he makes lots of money so she'll get plenty of child support.
Next, I wonder why it is that the men that throw away their families because they're bored, think arrogantly that they can do better, or want younger, thinner, prettier, can immediately find another relationship.
It all hits so close to home for me. I'm still alone, still lonely. WTF?
Just what is it that keeps me from dating? I find people I'm interested in. I never know how to pursue this. I am NEVER approached by men.
Do they sense some weird insecurity? Is it simply because I'm fat? I have no idea what the deal is. I do know that my ex still isn't perfect, but he's found someone.
She's great by-the-way. I do hope their relationship works out because my kids love her.
But what the hell is wrong with me? Wish I knew.