Anything between Alex and Dave. For example, Season 1, episode 6-Alex returns her engagement ring so Dave can sell it to raise money for his food truck, showing she wants him to be happy despite their past.
When Alex gives her speech in the Season 1 finale about not making the same mistake she made.
When Alex and Dave hold hands in the Season 2 finale.
Season 3, episode 3 "Boys II Menorah", Dave shows he's willing to make some real effort in his relationship with Alex, in classic romantic comedy fashion that gets tilted on its head for laughs but is still moving.
In "She Got Game Night", after Penny makes the decision to break off her engagement with Pete, all of her friends immediately make the effort to support her, most notably Max. Although he had previously reacted to the news nonchalantly (having to pee at the time), he ends up giving her a very heartfelt speech displaying the depths to which he regards her as a person and friend.
Max: Hey, hey! We are not gonna do this. We are not gonna cry! We are gonna celebrate! Because what you just did was make an incredibly strong and brave decision. You're a big girl now, and I'm proud of you!
Jane: We're all proud of you.
Max: See?! Make room, people, because there's a phoenix rising! (lifts Penny up over his shoulders)
In the stinger, though another joke is made at Alex's expense for leaving Dave at the altar, the latter is quick to comfort her, though it's more used as a joke on how Dave should have predicted it with his newly-realized "psychic powers".