Alfred had somewhat of an oral fixation. Luckily for Ivan, this manifested in a love of giving head. It was amazing how much getting someone else off could get to him. He loved the feeling of his jaw and throat stretching to accommodate his lover, the intoxicating smell of him. But most of all, and apparently most strangely, he loved the taste of Ivan's cum.
Of course, it wasn't like it objectively tasted good. Jizz was an acquired taste at best. But there was just something about the taste and feeling of Ivan unloading in his mouth that he loved.