My husband really loves fishing but I just can't get into it.
That sounds difficult. What is it about fishing that you don't like?
It's boring and I don't understand how he likes it, but I guess that's his right.
If you dislike fishing but your partner enjoys it, then it is good to compromise and let him go fishing. You don't have to enjoy everything your partner does; it's healthy to have solo hobbies, as long as that's not all you spend time on.
I would like it if he goes by himself more often, I really don't enjoy fishing.
I think letting him go fishing by himself is a good idea. Maybe there's another hobby that the two of you will enjoy sharing?