Couples believe it is very important to be overly public and mushy about their romance. This is because such behaviour made them very uncomfortable when they were single so it's important to alienate others now they're coupled up. It's not hazing if kissing is involved.
Couples get depressed when they can't be physically touching or sitting next to each other.
All couples need to make use of generic nicknames for each other and cliched descriptions of their happiness because every couple's love is both uniformly perfect and unique.
Couples can never "help it" and thus need to be treated with more sensitivity and respect than individuals.
Long-term couples are allowed to take a disproportionate amount of offence to the allegation that their relationship comes first and their friends second.
Once in a couple, there is no reason to assume that friendships that predate the relationship cannot handle the addition of an extra person at every meeting.
When a couple becomes two singles again, it is legitimate to contact (former) friends for the first time in months or years with an interest to "catch up". Any negative reaction to this action is uncalled for, irrational and hurtful.
Couples are always right. You can be sure of this because there are two of them and one of you.
There is no correct way to deal with a couple being physically affectionate for a sustained period of time right next to or in front of you. It is best to cease existing to avoid a) offending said couple or b) projectile vomiting.
It is never insensitive for a couple to be physically or emotionally intimate in your presence. It is the right of those "in love" to share such a beautiful bond with everyone else.
Couples reserve the right, after any of the aforementioned public displays, to say they don't want to talk about personal matters. After this statement it is not acceptable to laugh or roll one's eyes.
Anybody who is irritated by a couple or couples, regardless of their own relationship status, is just jealous and bitter.
Monogamists are optimists.