When you are currently not in a relationship with a significant other.
It usually does not bother you, but the problems start when selfish and inconsiderate assholes rub in the fact that they have someone, and start saying they "love their oh-so-sexy boyfriends
" and start going on and on about what he/she does for them, CAN do, and blah blah.
NOBODY CARES HOW GREAT HE/SHE IS TO YOU!! If you're taken, and love your partner a lot, then good for you, but for goodness's sakes, at least show some consideration for SINGLE people! Some of these people may even be heartbroken ones, who have been abused by past partners, or just simply some that are sick of hearing about some stupid narrow-sighted people who only see either how "hot" their partner is, or how much money he/she has.
Talk about your partner if you want to.. but.. just calm down about it. Your life does not fucking revolve around him/her, so don't act like it.
single person: Hi. I am single.
taken person: HIII! OMFG I'm TAKEN by OMG the BEEESSTT guy EVVVEERRR!! He's SOOO cute and OMFG we go to MOVIES together and do FRENCH KISSES and all!! YAYYY FLOWERS and ICE CREAM and PRESENTS!!! He's SOOO awesome and makes me SOOOO HAPPY!!!!
single person: -_-.... *walks away*