Questions & Answers about Hann er ástfanginn.
- Hann = he
- er = is
- ástfanginn = an adjective meaning in love
So the sentence structure is:
subject + verb + predicate adjective
That is why ástfanginn is not acting like a noun here. It describes hann.
Er is the 3rd person singular present form of vera, the verb to be.
Because hann means he, you use the he/she/it is form:
- ég er = I am
- þú ert = you are
- hann er = he is
So Hann er ástfanginn literally follows the same pattern as English He is happy or He is tired.