Not of all of these reasons apply to everyone. Some men are dating for sex, others are dating for marriage and sex, for example. Also, “single mother” can mean different things*.
Men, especially men with game, have a choice in women. Some women have children, some don’t. Unless you’re a pedophile, it is extremely unlikely that a woman with a child has anything to offer that’s of benefit to you that a woman without a child lacks. Conversely, here are the downsides of dating a single mother, in no particular order:
1) The kid(s) will always come first for her, and that’s the way it should be. A woman without a child has much more freedom to be available for you. An unmarried mother should put her child(ren) first. The child is already dealing with not having a mother and father married to each other and living together, and needs parental attention. That child does not need to compete with you, and you don’t need to compete with that child. Even if you were to marry her, the child(ren) will always come first, whereas being with a childless woman means YOU come first. Having children in the mix complicates EVERYTHING!
2) Most relationships end. So you’d bond with her children and then you (and the children) would have to endure the pain of losing or restricting that bond with each other. That’s bad enough for you, but you should not be a party to putting a child through that.
3) Being around the child(ren) exposes you to false charges of abuse. If the child likes you, if you’re nice to the child, that’s no insurance against false accusations. It probably makes you MORE of a target. These children are more likely to have mental and emotional problems. Social workers know that children in these situations are more likely to be abused by their mother’s lovers, so they’ll be more likely to believe you are a culprit. Even if you are ultimately cleared of false accusations, the mere accusation can ruin your life. This reason alone should eliminate single mothers from your consideration.
4) You WILL have to pay more than if you date a childless woman. First it will start off with having to pay for babysitters, and then she will want to have “dates” on which the child(ren) will come along. So not only will you not be getting sex, but you’re going to have to hang out at Chuck E. Cheese’s AND pay for the child’s meals and entertainment. Depending on what is happening with the child’s biological father, how much time the child spends around you, paying for the child, and buying gifts for the child (think birthdays, Christmas, etc.), you can end up getting tagged for child support. All it takes is some judge or government official picking YOU to pay for the child’s needs rather than taxpayers. Finally, if you marry her, you will DEFINITELY be paying more.
5) A woman who has given birth can’t ever have a body close to what she had before carrying a child. This is not saying that having a child isn’t worth it, but this is not about YOU having a child. That child is hers, not yours. Her body was changed by something that is of no benefit to you.
6) You don’t want to be a father. She has demonstrated already that she doesn’t know how to effectively use contraception OR otherwise doesn’t make good choices because she made children with the wrong guy (most likely)*, and has demonstrated that she WANTS to be a mother as she kept the child. Once a woman is a mother, she is less reluctant to avoid pregnancy. She may WANT her child(ren) to have a sibling, and you don’t want to end up being Daddy. It doesn’t matter what she says as far as “I don’t want another child” or “I can’t get pregnant” or “I’m using contraception” or “I wouldn’t ask anything of you.” Women lie or change their minds about this sort of thing all of time**, and even if she doesn’t, a court can make you be Daddy, financially anyway.
7) You don’t want to be divorced. Especially since women are more likely to file for divorce, marrying a divorced woman means you are more likely to end up divorced from her. Second marriages have a higher failure rate than first marriage. Marrying a woman with minor children gives you about a 70% chance of getting divorced. And that's legal divorce. Some people stay legally married, but miserable.
8) You don’t want to deal with the child’s father. Even if you’re just dating her and don’t want to get married, if the father(s) of the child(ren) is/are in the picture, that is likely going to be even more of a hassle for you. Even if a biodad isn't in the picture right now, he can always resurface and wreak havoc unless he's dead.
As you can see, whether you’re just looking for sex or you actually do want to get married (= legally obligating yourself to give at least half of everything you’ll ever earn to a woman, being held legally/financially responsible for any children she births during the marriage whether they are yours or not), you should avoid single mothers. This is written to protect men (and, somewhat, children). None of this is to say single mothers are bad people and certainly not to say all women do the things I listed. Some do, and men should protect themselves.
*Women are “single mothers” for different reasons. While the term should be reserved for never-married mothers, it can also refer to divorced mothers and widowed mothers. Unless she was widowed because her husband was killed through no fault of his own (as opposed to guys who committed suicide, or had unhealthy lives, or were involved in crime), she picked the wrong man and/or treated him like crap. A few single mothers used a sperm donor, and those women think men are not important. [SINCE I HAVE RECEIVED MULTIPLE COMMENTS ON THIS, please see what I wrote here about WIDOWED MOTHERS.]
**Never trust a woman’s claims she can’t/doesn’t want to get pregnant (unless, of course, you WANT to have children with her). Assume she is fertile and will want to have a baby.
Here's how to exit a relationship with a single mother if you're already in one.