Losing is never fun, but chess rating fluctuates a ton, so it is inevitable that you learn some days will drop rating (and that is okay). It is better to judge to continue playing or not more around how you feel and how well you sense you are playing. Once you notice you are beginning to tilt, or play less well, then it is usually better to stop chess for the day and try again another day.
Sometimes you can "fight through it" and make a rating comeback, but most of the time, it is better to continue when you are feeling more "in the flow." Implementing a stop-loss system could be valuable if you have the discipline to follow it, but ultimately the key should be to not obsess over rating at all (although probably everyone worries about rating a bit more than they should including myself)
Keep the emphasis on learning and improving, rather than on rating. If you can do this, then long-term your rating will go up as it catches up to your ability
Chess hasn't impacted anything outside of chess for me really. It shouldn't affect friendships and you probably shouldn't be missing all birthday parties to play chess. Like any other hobby, it is about managing when you want to play it and when you want to do other things (like birthday parties)
How you all manage losing in chess game after game? When it comes to losing I've noticed one thing that I can't leave chess until I win the same amount of games. Also, does chess affect your relationship with friends? I skipped all the birthday parties after I joined this website.