Here's the evolution of my decision to eat out twice a week on average and spend ~$50/month:
I started out working and supporting the family on my salary alone, and we were just scraping by after I made my significant 401k contributions. Going out to eat would have taken a chunk out of my 401k contributions at the time. So I would rarely go out to eat - maybe 1 time every month or two.
DW finished school, recovered from having our first child, and then found a good-paying job. She went out to eat frequently with her new coworkers to socialize mostly (she was tired of being socially isolated while stuck at home w/ the kid).
I kinda freaked out that she was going out to eat so much because I was still viewing our budget and spending habits in terms of our old household income when only I was working. After looking at our spending for a few months, I realized that it really wasn't that expensive for her to go out and eat 2-4 times per week relative to what we were saving and investing.
That's when I loosened the purse strings, quit "harboring resentment" towards her for spendthriftly wasting our money on dining out, and started joining my own coworkers for lunch occasionally. It definitely helps break up the work day and make it more tolerable.