Yeah Anna is getting influenced by others, but still that isn't the best reasoning, cause I feel like most logcial people would believe their spouse, over men that she barely knows for the most part.
Imagine a reverse situation between husband and wife.
Husband faces changes in his work, gets a promotion and increase in work and responsibility.
Marriage is already a bit strained with the kid and problems in wife's family business.
One day husband receives photos of his wife going down on a dude from the gym.
There were already some signs of trouble (perfume, panties, etc.)
The wife tells the husband you are being unreasonable and silly, it is not what it looks like.
So according to you the husband should just say "oh, ok then, everything is fine"