I'd rather get shot than have sex, so no, I wouldn't. Most people are assuming that she is no longer dating the father. She was serious about the father, so I doubt she'd cheat. A lot of people sleep with people they just met, and that's okay. As long as there is consent then I'm in no place to judge.
Casual sex isn't harmless. You pretty much jeopardize your chances of having a committed relationship in the future, as it becomes harder to get people's trust/take you seriously. It goes for both men and women.
Of course though, in a city, you don't risk the same things as if you were living in a village of a hundred people. But there's certainly a cost, word spread.
There again, it goes both ways, but you really have to wait until enough emotional attraction has built up, which is the OK sign. You can then let the person tell you more clearly if he/she's interested or not into something serious.
So no, unless you're sure you don't ever want to commit in a serious relationship, don't sleep with people just because they're attractive. They might actually be offended you don't want to take the time to know them more seriously before asking to see them in their most vulnerable form.
And ask them their STDs test at least, please. Make sure you can trust them on it as well. Make sure you can trust them to not try anything funny. Make sure he's not looking for a serious relationship with you, if you don't want one, tell him directly.
Morally... If your way of getting it is to play with the person's feelings, then meh, not really moral. If you come off entirely straight, it's another thing. But it's about wanting sex from someone without really caring about what they are really is inside... Kind of treating you like an object, only wanting something from you because of your appearance.
Now if both consent of treating each other kind of like objects, good I guess, but not everyone sees it as something to be treated casually ╮( ̄▽ ̄)╭
Honestly, if pretty much a stranger, I'm mostly totally freaked out when it happens and try to spot every options I have in order to stay safe or run away from a conversation with them if they're being too clingy and won't leave me alone. Not a pleasant experience.
If it's someone I actually at least remember their name, yeah, it can get offensive depending on the tone. If they're like "I know you want to sleep with me", berk. If not, I mostly feel harassed. WAAY too soon to ask such a thing. And they could've asked my two cents about that kind of sex instead before asking such a thing. It's less intrusive and they can pick up the hint.
"Casual sex isn't harmless. You pretty much jeopardize your chances of having a committed relationship in the future, as it becomes harder to get people's trust/take you seriously. It goes for both men and women. "
This is such a massive crock of shit. You've got some major hangups.
I personally agree with Nnene. I don't want a man who was a player and slept around.
Casual sex is not harmless sex. it does take a toll on a person. If not emotional, health wise. you have to be concerned abt. not just Std. , Hiv and now Zika. Those are quite real. You can carry Hiv for years and not know it. That is not a hang up.
One time I got into that awkward position where I was with some other people in the morning talking about their drugs and sex adventures lol.
There was one case where one of the guys was talking about that time one girl he had casual sex with just stopped taking the pill without telling him. He was literally having panic attacks when he knew about it, thankfully she ended up not being pregnant.
And he also talked about another guy, who dated a girl who had lots of "experience", and well and STD. He decided to have unprotected sex, since hey, he was so convinced they "were meant forever". It took maybe 2 years, which is fair enough I guess lol, and they broke up. Woohoo.
You never know in what kind of situation you might end up in, they're things that really happen, believe it or not ╮( ̄▽ ̄)╭
The people who can do it without any emotional toll are rare though. And people lie/are not aware about their STIs.
They're not looked down upon unless they got it in the most stupid way, were being way too careless and now whine. But regardless of that, even less people would want to date them, for obvious reasons. Nothing to do with looking down upon, but it's just a bit scary you know.

Girl don't go spreading your legs just because you find the man attractive and hot. Kurose burn that lady!