〜がたい

その話(はなし)は信(しん)じがたいです。

Sono hanashi wa shinjigatai desu.

That story is hard to believe.

がたい is a difficulty of the heart, not of technique

忘(わす)れがたい思い出(おもいで)です。

Wasuregatai omoide desu.

It is a memory hard to forget.

It joins a limited set of verbs, 信じる, 忘れる and 想像する chief among them

にくい のほうが幅広(はばひろ)く使(つか)えます。

Nikui no hō ga habahiroku tsukaemasu.

にくい applies far more widely.

読みにくい works; 読みがたい is barely said