For the person who is not a single parent, please read this post to acknowledge how things are worded when speaking to a single parent. Remember that they more than likely did not choose to parent alone and your questions can come across, "loaded" or uncaring.
"Mr. or Mrs. Right is out there. You'll find each other some day and then you won't have to be alone."
Not every single parent is looking for a significant other. Sometimes the pain is so deep that cultivating another relationship would be detrimental to the children involved. This statement can make the single parent feel inadequate and that they should be with someone to live up to societal standards. This simply is not the case.
"You look exhausted! Where do you find your energy?"
To a single parent, this is the last thing they want to hear. Typically they do not have energy so finding it would be amazing, but telling someone they look exhausted is nothing short of an insult.
"This must be really hard on your kids"
People assume that single parented kids are damaged. The single parent strives with every ounce of their effort to ensure that their kids are taken care of and have the best life possible. Confirming their fears that their kids are not okay and that they as a parent may not be doing "enough", is hurtful.
"You should be proud of yourself!"
This can be very demeaning. You wouldn't walk around telling this to married parents, so why the single parent?
"I don't know how you do it!"
The simple answer is because we have to and we want to. Circumstances aren't always as bad as they seem and we enjoy being parents too. The load is just different.
"What do your kids do while you work all day?"
Again, you typically wouldn't ask this of a married parent, so why the single parent? Their kids do what your kids do; they are busy being kids. Answer is simple. The kids are most likely in daycare situation or are being watched by a relative.
You might say: "What kinds of activities have you planned for your kids while you are at work?"
"You need alone time."
The urge to say this is understandable because everyone needs alone time. Problem is that single parenting can be very lonely at times. Even with kids running around, the lack of adult communication can be isolating.
You might say: "When can I babysit for you?" or "Do you need time without the kids; how can I help?"
"Where is your kid's father/mother?"
A question you really shouldn't ask anyone. This is very personal and you'll know if the single parent wishes to confide in you.
You might say: "If you feel comfortable sharing, I'd love to know how to pray for your children's father/mother."
"You must be so lonely!"
This statement is really rude and makes it sound as if anyone without a significant other is lonely. Some single parents are perfectly happy and for those that are lonely, this is a painful exploitation of their feelings.
You might say: "I'd love to hang out with you sometime."
"My husband/wife was out of town for a couple days and so I know how you feel!"
OR "My husband/wife was sick over the weekend and I had to care for the kids alone. It's exhausting and my heart just goes out to you!"
The single parent day in and day out experiences parenting alone. There are great days and not so great days. Spending a few hours or days without the other parent is absolutely not the same. When this is said to a single parent, it belittles the world they live in. No one can imagine what they have not experienced. Spouses spending a short time away is not equivalent to single parenting.
You might say: "I have had a taste of what it could be like to be a single parent. Let me know how I can come alongside you!"
Most people mean well with what they say and ask and it can be difficult to know how to relate to anyone in another life circumstance than yourself. The key is to think before you speak. In most cases, the single parent if they know you well enough, will recognize your true intentions in these questions and statements and will not or should not take offense.