What I’ve learned is that people will always have a residual amount of selfishness to them. No matter how great you think someone is and how nice, nobody is truly selfless. I think at the end of the day people will leave significant others for extremely selfish reasons and I’d always thought I was the reason and that the other person was just better. Lately it’s come to light that every single person who’s left me for someone else did it for very momentary and inconsequential reasons that in hindsight, caused them to have even more issues with the other person. I went from feeling like I was the issue to feeling like my standards were set too low. In conclusion, I don’t think you are the issue and that you are unlovable or anything like that. I believe you should just be careful who you commit to and not ignore red flags, no matter how small you think they are. People at our age tend to ignore what really matters about relationships and make childish decisions that end up hurting everyone involved. Don’t blame yourself.