For me, there is no argument about Sage being loyal in marriage. My entire premise is that she is prone to outbursts and jealousy. You mix those two things with marriage and it won't end well. Sage is the kind of wife where if you come home from work unexpectedly late, she is sat at the table with her arms crossed and a cold, uneaten dinner in front of her. And the first words out of her mouth are, where the fuck where you and why didn't you call? You SOB, you're sleeping with that bitch secretary aren't you?
Meanwhile, the real reason you're late is you decided to get some spicy Kung Pao chicken from a street vendor and it wasn't sitting well with you. As a result you had to spend 45 minutes on the commode burning your arsehole out and you really didn't want to call her from the toilet. But she will never believe it.
Regarding Bella, the age (while certainly a factor) wasn't really the primary concern. Rather it's her mental state. Let's assume she isn't an axe murderer and she is just depressed. What a buzzkill. If MC and DPC can't solve her depression, then she is a no go for me. No smile, no laugh.....then no sale. Bella would be the kind of person whom you take to amusement park to have some fun on the rides and she would be like...
Sorry, but I like happy people. A lot of the women in the game are great for a short term sexual fling, but are not realistic marriage material.