Re: Why won't my sims get married?
Other things that can increase your chances are special romantic situations like 'Love Day', a really romantic date, the Romance Festival, etc. Also, giving certain gifts that are romantic can help.
Just a thought... does one have a trait like 'soul mate' or 'romantic' or some type of trait that may increase difficulty for romance or create an exceptionally high expectation level for a romantic relationship?
If the turn down is one-sided (one sim) and the relationship & romance are maxed, both are high in the green for all needs, and both are very flirty and the sim is still refusing, I would try going into the game through the hesitant sim and having them ask the other one.
Maybe if this couple is a bit difficult, once you get the 'yes' you may want to then elope right away and have it a done-deed.
Sorry for repeating some of the excellent comments by @jpkarlsen. 🤔
Also, even though in my games my sims never 'woo-hoo' before marriage, I have occasionally moved them into the same home since that makes it WAY easier to maintain the relationship and romance levels, and control both parties as needed to raise moods, needs, etc. If you have a full read on and control over both sims your job will be MUCH easier. Also, you don't have to give them a choice in the matter... just go to manage households and move the sim into the lot/household.
