If you have and felt that you are the only one to suffer in this way (i.e. pressure to attend after-hours dos, travel more for work than your coupled colleagues, and work weekends) then the article - Single people feel discriminated against at work by Polly Curtis of The Guardian should be a starting point in redressing an increasing imbalance in British workplaces.
According to the article in question, "most single people are happy being single but many feel picked on at work, left out of couple-dominated social occasions and penalised financially." What is more, "six out of 10 single people who work claim to have experienced some form of discrimination in the workplace because they are not romantically attached."
A "singleton", by-the-way, is defined as being widowed, separated or otherwise not in a relationship and not planning to get married or move in with a partner in the next 12 months.