Netoge no Yome wa Onnanoko ja Nai to Omotta?, Net-juu no Susume Recommendations
Both anime are about the social aspects of playing online games, and feature romance and crossplay.
Netoge no Yome is about schoolchildren, but Net-juu is about adults, so take of that what you will.
Both contain in game/IRL relationships
Both involve romance in a MMORPG game world where the girl completely is off her trolley to hate the reality of life.
Both are stories about people playing an mmo online. In Net-Juu, both mc's use the opposite gender and start to fall in love with each other in the game. In Netoge no Yome, the male mc confesses to a girl in a game and she tells him that she is actually a boy in real life.
Both series socializes via playing games. The story is similar to each other. They know each other in games as well as real life. The romance is pretty good as well as the comedy.