Just not horny enough?

Ok so when I have sex with my boyfriend everything just feel good. There’s never any pain and it feels right. But when I use my vibrator or dildo it hurts when I try to insert it. I use lube (which i dont need when I’m having sex with my boyfriend). It’s not that it’s just that it actually hurts to get it in. Any advice? Even if I cum before I try inserting it it still hurts..