She gets along better with him!

This may make me sound as if I am paranoid, but my girlfriend who has been with me for six months or so is getting too close to one of her male friends. They are always chatting, and it feels as if she talks to him more than she does with me. I don’t want to come across as possessive or insecure, so I don’t say anything to her about this, but it is bothering me a lot. I catch her laughing at something he has said, and it feels as if she is dating him, not me! She never laughs like this with me, and I am always wondering if she will break up with me and be with him because he makes her happier. I don’t want to lose her, but I don’t know what to do. Should I tell her how I feel?
Yes, you should, because relationships that last are built upon trust and the ability to communicate without fear. If you are worried about coming across as possessive, you are allowing your mind to convince you that your girlfriend may choose someone else. This may be furthest from the truth, and you owe it to yourself and to her to find out how she feels. If she wants to be with someone who presumably makes her happier, there is nothing you can do about it. However, the fact remains that she is with you, and that everything you see is speculative and prone to misinterpretation. Tell her why this is bothering you, give her a chance to talk about this friend, and avoid jumping to conclusions without access to real information.

I dumped someone because he was still using dating apps, but he asked for another chance. Two days ago, I found him on an app again. What should I do?
This is disrespectful behaviour. If he is looking for people on dating apps, it’s obvious that your relationship with him isn’t working. Why complicate it by giving him the benefit of doubt?