You need to get yourself out there. I've been trying to do this more often. Every time someone asked me to go somewhere with them, meet them somewhere, or suggest something that I really didn't want to do - I did it anyways.
Keep you mind constantly occupied with other things and get active.
A new partner can definitely kill old feelings for the ex. But make sure you are absolutely ready to date. This can be up to a year or more... . you'll know when you are ready to commit. I'm a year into separation and I haven't had much desire to even go on dates. Just don't be a like a BPD that jumps on the first thing that comes into focus!
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