I choose to skip it by not returning to Yhilin Palace. After all she served her purpose and she doesn't deserve to marry Simon when many others probably want to do the same thing and they have been with him longer than she has.
Janine RP maxed are checked more then one time, and before the ceremony it'is impossible max her.
the only girl with simon interested in a marriage (of sort) is carina, (well sarai too, but it's another story) simon and carina know each other long before simon meet janine, but the relation start with the queen a lot before the priestess. (in game time between foiling the cup and the marriage at the earliest moment the are three years at minimum)
and if you had spent a couple of minutes reading the harem response no one object it, and carina say two time (in the chapel and a dialogue in janine room after that) her happines for janine.