Is this conversation a red flag between exs ?

[LexiAllen]

the guy I’m dating ex girlfriend posted a quote on her story saying “she’s hard to replace, and unforgettable, hard to come bye”. He responded to her quote and texted her saying “yea yea yea” . she responded saying “you know it” then he said “mmh idk”. She then replied saying “you know you still like me” and he responded saying “how are you so sure” ….

why did he even comment on her post saying that?

You are obsessing over the 'why'. It's not important. He likes her still and is arranging to meet, again, why he likes her doesn't matter. Just dump him, preferably without telling him why, because that will mess with him more and gives him no chance to formulate excuses.
He comes across as a guy who is incapable of turning anyone down when it's offered. Listen to her, she's already said that she knows he messages other women, and now you know that is true. Not a person loyal enough for a relationship, he's just not good enough. The why will be nothing to do with you, it will be embedded from his childhood. Let's say you magically knew why, what's your next step? You know there's a reason so you forgive it all?
This was obviously a sad woman who has tied herself in knots for his attention despite knowing he still tries with others behind her back, a woman who will accept a hookup, any scraps he wants to throw. Don't become her, have more self-respect.

Op, it sounds like you are realy struggling with this. I can totally understand the wanting to know every single why and how, as I'm the same. I need answers to absolutely everything, its just how I am.
And it sounds like you are hurting alot over this because you are a loyal and trusting lovely person and you likely feel a bit used or feel second to her or something. And questioning, was he even real with you.
It hurts. Alot. And for someone who simply wouldn't do that to someone else it is very very hard to understand.
But the guy is a total waste of space and a waste of your time. The fact you have met your arsehole at 23, think of as blessing. Some of us end up marrying ours and wishing we'd kicked them to the kerb when they first showed signs of arseholedom.
As much as you are hurting, think of it as that blessing in disguise. He has shown you who he is (an arsehole) and you've seen it (who gives a shit if you snooped, good job you did!) and so you can get rid of him.
There is someone out there with the same morals as you, who will treat you with the respect you deserve and not hurt you for the world.
That is the one you want in your life. Not this piece of crap.
Don't think of it as he prefers her over you (he more than likely doesn't, he is just one of those shitty men who like to have their cake and eat it and don't care who they tread on while doing it). So consider him dead to you and move on. He is not the man you thought he was. And even if he tries to talk his way out of it (he likely will, including begging, tears, telling you all the things you want to hear) don't fall for it.
He is not a nice person and you deserve a nice person.
Dig up some courage, drink some wine, go out with friends, eat ice cream - whatever it is that gets your mind off this twat and don't give so much as a glance back. I mean how dare he? Who does he think he is?
Know your worth, my love.
HE is not worthy of YOU.

So what? The poster I think you're referring to has given her opinion. There are multiple differing opinions on this thread all probably correct. You will ignore all of them.

In my opinion, he is doing all the chasing of her.

He posted on his story that he only talks to a few people a day… she commented this
Her - “shut up you know you talk to loads of women”
him- I could but I don’t, they try though”
Her- sends a rolling eye emoji
Him-“ I’m trying to be young and turnt like you”
Her- “I’m trying to be married and in the house”
Him-“ lmao now you wanna to be married”
Her-“ I’ve always wanted to be “
Him- “I’m just going based up off what you told me”

Seriously, these people are 23? You all sounds like a bunch of 13 year olds. Grow up.

He responded to her because he wanted to. End of.

stop over thinking it and just understand that he doesn’t respect you or your relationship or feelings.

This is cringe, teenage drama, surely none of you is actually 23. if you are, grow up.

They deserve each other but he should dump her for terrible grammar.

how do people fall for others again if there not together/talking ?

I’m having some difficulty believing this is real. The questions the OP is asking are a bit too ridiculous.

Oh he's hasn't fallen for her, he just wants to fuck her fgs! But whatever it is, he needs dumping immediately

That’s what I said

@LexiAllen asking but why repeatedly like a 5 year old will not help you here. just move on, get some therapy to understand your own issues (you seem very unhealthily fixated on this man) and just work on developing yourself before jumping into another relationship.

This is actually painful to read. Just stop!

He's chasing her, for whatever reason. Let him go!

Let me guess, he was "the one" cos you'd been "Facebook official" for all of two months?!