In order to get married: you must have a relationship level of 250 or higher.

At that level. you only have to date & speak to your partner to trigger a proposal, provided you have been on more than a couple of dates.

You are required to finish a quest in Florence to get the ball rolling on marriage planning (Maria calls and asks “have you ever been to Florence?", level 6+)

This triggers additional tasks that must be completed prior to the wedding event.

 If you still have anyone listed with 1/12000 or more and the heart icon is whole, you will still need to break up with them.  If your current partner believes you are cheating or if you make it public that you are still dating others (Ray Power will announce through Star news that you have been seen dating someone else) We believe that in cases where a player has multiple active romantic partners, even if the relationship is only 1/12000, that this may be preventing the proposal from triggering.  

There are several stages to each level of a relationship.  To clarify, this is the first step of the proposal ladder.  You'll go through several stages of the relationship before the partner proposes for example:

1) Getting serious

2) The I love you's

3) Soul Mates

4) Proposal

These triggers are present upon reaching each max of the relationship meter.  A pink dialogue message will become present over your partner when a trigger has been reached and a new stage is about to begin. 

As long as you do not decline the advances, you will move on to the proposal on time.  However, if you do decline, the proposal will be significantly delayed as your partner does not like rejection so will be hesitant to offer again.  This does not mean you cannot get married, however.  You will just have to continue dating over and over until your partner has gained enough confidence to ask again.