I disagree they called each other by their FTL names and kissed. They probably know by now that their SB lives was a farce; the strain will be between each of them and Emma.
I think there will be some strain between Snow and Charming. They’re both going to remember their Storybrooke selves and how they felt. MM was incredibly hurt by David and although Snow will know that Charming wouldn’t have done that, that hurt doesn’t just go away.
Charming would feel guilty about how he behaved as David. Even though it wasn’t his fault, he would be aware of how much he hurt Snow.