As a culture there are certain 'accepted' behaviour patterns, and people become uneasy when individuals buck the trend.
For this reason, a lot of people marry and have children, not because they have thought it through and it is what they really want to do, but because friends and relations put pressure on individuals to conform to the 'norm' because it makes people feel safer and more secure.
So - as a single person, you get the nonsense you have outlined, even though it is unrequested, and often bordering on offesnive. In the same way, as a newly-single womman, you will be perceived as a threat by some women in relationships because, of course, you are 'hunting' for another man (!)
My wife was separating from her first husband when we met, and I son got the "Well, the kids needs a dad ..." garbage - they have a dad, OK a lousy one, but they do have one. Then we married, and the tgalk shifted to "Well, you'll be wanting one of your own now ..." - so what are our daughters - houseguests??????
It is so annoying, but I do belioeve that this pressure leads to unhappy marriages and families because people conform to pressure against what they really want and need.
Hold your head high and be an individual. A relationship is like chocolate, not oxygen - nice if you fancy it, but not life-threatening if you don't have it.
Tell people that you are toying between joining a nunnery and trying lesbianism - do it with a straight face, and you'll not hear a peep out of them on the subject!!!