Having sex in Starfield reduces the grind of several Xbox achievements

Having sex in Starfield gives a 15% XP buff from 'Emotional Security' status effect
Buff helps unlock demanding achievements like reaching level 100
Need to romance and marry a companion first before getting buff
Works as Starfield is on Xbox/PC Game Pass and Cloud Gaming
Players doing strange things in Starfield like gathering 20,000 potatoes

trueachievements.com

Relevant topic timeline:

9/6/2023

Having Sex Daily In Starfield Is Actually A Fast Way To Level Up

Bethesda Game Studios' upcoming game Starfield will reward players with a buff called "Emotional Security" and a 15% XP boost for spending the night with their romantic partner in the game.

9/5/2023

Starfield romance options and how relationships work

Romance in Starfield allows players to deepen their relationships with select companions, unlock companion quests, and even marry one of them, with each romance interest having their own preferences and questlines.