Goes FABULOUSLY with
Matteo. I myself prefer
Seraphina, but
Serafina is all right as well. I just think the "ph" softens the name a tad.
Apparently a common nickname (in Russia I think?) for
Seraphina is Simah. I think that name is adorable.
If
Seraphina is too long, what about
Seraphine? Knocks on syllable off, at least ;)