My girlfriend and I have been together for almost four months, but we argue all the time because she thinks I’m still in love with my ex. I keep telling her that this isn’t true, but she brings it up a lot. I don’t know how to convince her and the more she sticks to this theory, the harder it is for me to commit to this relationship because I feel as if she isn’t even listening to me. I don’t want to break up over this, but I also don’t see a way out because the frustration is constant. She is always using this against me, and it becomes the only point when we are trying to resolve some disagreement. Should I give up on this if she can’t let go of the issue?
If your girlfriend feels as if you aren’t in love with her, your relationship isn’t going to last. The issue isn’t your ex as much as it is a lack of faith in whether what you have is real. The onus of making her feel secure is on you but, if nothing you say or do can change her mind, you have to accept that there is no future here. A relationship starts with the basic premise that one’s partner has feelings that are reciprocated. If that isn’t present, and neither of you can move past it or find a way of putting this behind you, there will be no future. Tell her why this will end without you both committing to making this work and if that doesn’t lead to any significant change, you should assume that this isn’t going to end well.

How do I tell my friend to stop stealing attention from guys whenever they are talking to me?
A friend is someone you should be able to have any conversation with, even if it’s difficult. If she can’t understand where you’re coming from or why this bothers you, try changing how you approach the topic and be more patient.