At the end of the day, it only matters how much love you show your current partner and the effort that you're putting into the relationship. If you aren't doing those two things then everything about you, including your exes, will start to bother the new person whether you bring it up or not. They will start noticing your lack of effort and affection compared to your last relationship.
For example, the reason those mos ab don't appear jealous about the current wife is because the husband spoils them. We're talking about men who aren't even divorced from their wives! These mos ab should be enraged. Same reason why some women have the audacity to be a second wife/niam yau. They have the husband's attention so it doesn't bother them too much if the first wife still lingers.
As for me, I've come to conclude that many men are full of bs. In the beginning when they pursue you, they want to convince you that they're all that. They will tell you how much they did for the ex(es) who didn't appreciate it. Then when they finally convince you to give them a chance, you notice they don't do nearly half of the things they claimed to have done for the ex(es). There are two ways to look at this:
1) feel super jealous
2) realize that he was lying through his teeth.
If you give it enough time, the reason is always the latter.