Is it helpful to stay single if I am not going to become a monk? In most Buddhist traditions, monks are expected to follow an austere life without being married or involved with another person, but what about lay people who are not going to become monks?

Personally, I've reached what most people consider mid-life and I'm getting too old for any monastery to accept me, but I'm sure this question applies to lay people both older and younger.

I am under the impression, monks are required to be single because of the attachment and desire that arises when being involved. However, a good number of monks do not live among lay people which I imagine would make it easier. It seems like lay people would benefit though, and when their time on Earth has expired also make it easier to let go.

However, I don't have a teacher nor do I have access to one so I wanted to reach out to the community to see what their impressions were. My guess is that it is helpful but a personal choice that differs from individual to individual. I mean 'helpful' in the sense of being closer to Nirvana or Enlightenment.
What matters is what you do when you are single. If being single means using prostitutes to satisfy one's sensual desires, it could lead one further away from the path as compared to a person who restrains himself to one woman and practices loyalty, kindness, doing good deeds together etc. 

But if being single means being celibate and using one's free time for meditation etc., one would generally have a higher chance of progressing in the path as compared to the average family man. 

In the time of the Buddha, there were monks who went to forest for seclusion and ended up having sex with monkeys. So what really matters is what you do when you are single.