Why does he say I deserve someone better?

I’ve recently started dating someone new and I think he is great. However, he always thinks he’s not good enough. He said in the past, he’s been hurt and his ex always insulted him. He had two exes and apparently they both insulted him in arguments and what not. He dated his first ex for three years and the other for about 6 months. He’s been single a year and a half now.
Maybe his past has made him this way.
I’m not sure if he just has low self confidence or he wants to let me down gently.
How should I approach this