And just to add to Ksand's reply. What you read from people on other forums about seemingly unjust refusals, is in almost every case, not the full story.
We met and got engaged in Spring 2016.
We married in the US in May 2018 -- after several meet ups and speaking every day.
However my wife's first trip to visit me in the UK in Aug 2016 failed -- because she was refused entry citing insufficient evidence of ties to the US. We were open and honest and told Border Force we were engaged. At least they can see from this that we had a relationship back then!
After two failed attempts we finally got a visit visa in 2017. Not easy to prove intention to return home when you're openly also planning a life in the UK and already shutting down the old life in the US!!! That successful application was a huge task for us.
She visited me on the visit visa for 2 weeks in November -- accidentally arriving a week before the visa start date! And was let in.
She then visited me on the visit visa for 5 months from Xmas.
On the plus side we had 6 months of contact to help us be genuine and subsisting. On the downside they might not like her staying so long.
Also it's difficult to think of everything and easy to overlook potential discrepancies and technicalities. E.g. One thing I just thought of is that our rental property particulars do not not give measurements of the rooms, just photos of each room!