I am in love with my boyfriend. He loves me back, but there was this problem when he cheated on me once. A few months later I found him talking to the same old girls he got hooked up with. He does everything to keep me happy and puts so much effort into making me smile. He affectionately cares for me when I am near him and misses me often as well. He wants me to be in his life. He says I'm the last girl he kissed. After all of this, he says he has stopped talking to them, but he is often late replying to me. It worries me. The fear of being torn away keeps me distracted from my studies most of the time. Please, I need help for I don't want to hurt that poor soul either. How should I handle it? Should I leave him for his own good?
The purpose of dating is to get to know a person before committing to him in marriage. I assume by "cheating" you mean that he had sex with other girl. This tells you a bit about his character -- that he lacks self-control.
It appears you keep him around because he pays attention to you, but I don't see much indicating that you are strongly interested in him as a person beyond your statement that you love him. Nor does there appear to be much trust in this relationship, as can be expected with the other person hasn't been true.
Should you leave him for his own good? This isn't a matter of punishing him. It should be a decision about whether he would make a good husband. If he doesn't appear to be stable, you end it because he isn't the man you want to marry.