3 Ways to know whether your lover will treat you badly in future especially when number 2 and 3 happens

You think he's being open with you, yet something doesn't feel quite right. He talks about the future and says just what you want to hear; he wants marriage and kids. Naturally, you assume that since you two are dating, this future dream of his includes you. But does it? Something doesn't seem quite right and you can't put your finger on it. You find yourself second-guessing your feelings and questioning the truth of your relationship.

Poor Listening Skills. Your partner may be the apple of your eye but can be a bad listener when you have something to say. Whether you’re expressing your feelings about the relationship or are
discussing your dreams, you may find that your significant other seems distracted or not interested as you speak. Although it may not seem like a big deal, this can mean that your partner doesn’t care for you as much as you may care for them. As time passes, you may feel ignored or neglected in the relationship.

He talks about the future without including you specifically. He attends to your needs more than his own, usually out of guilt for not feeling fully engaged with you. He avoids disagreements, preferring always to keep things status quo between you. When you ask him directly how he feels about you, he's unsure and indirect. He may say he deeply cares for you, but follows that with, "I need more time," or, "I'm not ready for a full commitment yet." Your relationship seems to plateau at a certain point and stops growing.
A Wandering Eye. You may be too in love to notice your partner’s wandering eye when it comes to seeing other men or women, but this can eventually cause them to cheat and stray from your relationship. If you notice that your significant other is overly friendly with the opposite gender, it
can mean that they won’t be faithful in the future. If he still talking to her ex. And by “talking,” he means “totally still seeing and occasionally having s*x with.” This guy is clearly already in a committed relationship with his ex.

And guess what? Old habits die hard. Seriously though, the reason he's still speaking to his ex is that he's not finding that fulfillment from you. Stop trying to change him or make him choose you over her. You shouldn't have to fight to get a man's full attention