When we first start to date someone, there’s something that attracts us, whatever that might be. It might simply be that you want to have a date, lol.
Then as you get to know them you watch for ways you click and ways you don’t. With each date you note if you had a good enough time to want to see them again. Also, different people are at different stages in their lives for their purposes in dating. Some are looking for commitment and some are not.
When a comment or situation comes up that is enough of a deal maker or deal breaker, that’s when you know if they are not right or right or right enough for now.
In my progression with my husband, it was a good dating experience. Each date got closer and grew more affectionate. Neither said of did anything really off putting.
It wasn’t until after we were married our trouble began.

there was really no red flags to see that coming either, honestly. So, you really can’t ever be 100% sure. We’re still together, so I’m not sure I’m a healthy example TBH.