Actually, I only contradicted you on the point that Chris is the greater danger for their marriage because David would have a mental cinema of Chris and Ana after every sex afterwards.1. Yes, Chris is the closest to being the one to sleep with Anna, but only because he has been courting her for a long time.
Even if that happens, I don't think she will be emotionally attached to him.
I see instant regret and an attempt to hide what they did.
2. Jake, in turn, has just started, and as far as I can see, he has a game, he knows how to charm and keep girls.
Here I see the possibility of emotional attachment and great sex, which she lacks so much.
I think she will come to her senses and understand what she did only after he leaves her.
Again, these are just theories.
3. My David will never forgive betrayal (I hope there will be a choice in this case).
Whether Jake is the better lover doesn't matter at first.
If someone plays David in such a way that they don't want to cheat on Ana, then Ana shouldn't have any significant reason to leave David permanently.