We didn’t get one. They’re not getting married till she’s 80 or 100 or something for some reason
I think it's because if they marry they would be partners and then the "curse" will take place... So they would try to kill her in order to kill the vampire. Or at least, this is what I get ٩(๑❛ᴗ❛๑)۶
They got married, on paper, but didn't take the marriage oath. Millard is immortal but if he took the oath than he could be killed by killing his partner. That could be prevented by making her to be a vampire but she didn't want to be one. At least not now. That's why he'll wait for her decision even for another hundred year. Who knows in the distant future, since she is still basically an empty vessel. Anything could happen but for now, they're just enjoying their live together.
I don’t know if I accidentally skipped a chapter, but was there a wedding ceremony or was it not shown at all?