First, I'm sorry in advance of this turns out to be really long. My hamster's been running a bit wild, and it's making me feel insecure in my current relationship.

I've been in a relationship with a great guy for half a year. He shows all the marks of a high-value male. He's a great leader, and he's done a lot of things in the name of my happiness. However, I still feel insecure because he's close friends with his ex, his high school sweetheart.

They were in a long-distance relationship for the first couple of years of his undergrad, and then she broke up with him when she finished senior year of high school. I'm not sure why.

He says he was devastated, but that he then realized they weren't as compatible as he thought. He says he hasn't had romantic feelings for her in a while.

He says he loves me. He says he sees a future with us.

However, she's put in a ton of effort to still include him in her life as her 'best friend,' even though they're thousands of miles apart. He's her only close male friend. It's been years since they broke up, and I can't help but think she regrets breaking up with him and wants him back, and I'm afraid he's still attached to her and will eventually leave me for her.

I can't help but think she'd be a better partner than I am. Her eyes are bigger, her lips fuller, and her hair shinier. She's wittier. She shares more interests with him. She has eight years of history with him, while I have six months. I can't help but think he may not realize how invested he is in her, and that one day, he'll wake up and realize he doesn't love me, but her.

What should I do, RPW? I've been practicing STFU-ing, but deep down inside, this situation makes me feel really insecure, especially since I've been burned before.

EDIT: Removed most of the identifying details