Singleness can always change (if the person hasn’t entered the religious life), but being realistic here – when you’re way past a certain age, have never been married, and don’t look particularly good, how likely is it change? There are ten worlds of difference between being single, 25, and cute, and single, old, and not-cute. The young single person is far more likely to marry than the old single person.
We can remain open to marriage until the day we die, but the fact is, it isn’t going to happen for all of us, and how long do you keep trying to put your life on hold or trying to insert yourself (ridiculously) into the “dating game”? Eventually, it becomes more productive to simply live the life you have been (apparently) given. Being open to something doesn’t mean it will ever happen.