how to appreciate a good guy after a bad one

I dated my ex for almost 4 years, I'm so used to the way he treated me that when I met this new guy I have no idea how to act. This new guy is so so sweet to me, does anything I ask him to, sends me flowers, plans surprises, wants to see me as much as possible and he's just an all around great guy. My ex was super distant all the time, never told me sweet things, we hung out maybe once a week, never really did much with me. So now I feel so bad for this new guy, I'm really not used to being treated so well and I feel like I can come off really unappreciative sometimes and it really makes me think that maybe he is too good for me. He's literally everything ive asked for all these years so why is it so hard for me to accept everything he is? Has anyone else went through this and if so what can I do. 😞