It sounds like too much pith.
How is the sweetness?
If it is sweet enough you could add a little salt just a tiny bit at a time.
Or you could turn it into a chutney
OH got home and even though I told him it was a giant fail he tried some....
....
....
And loved it!!! He’s had a marmalade sandwich and just spooned it into his mouth.
I said it was too bitter and tasted like when you sink your teeth into an orange peel and it leaves a horrid taste in your mouth for ages. But he said no it was nice and could even do with being more bitter.