The last thing you should do is to act out of loneliness. There's a there's a reason that person is in your past and I genuinely believe that with enough vulnerability, they'll agree it's probably best for them to stay there. When you are lonely to keep your standards high like I think when you feel lonely It's the best opportunity to raise your standard even further and to keep them there. If you just want to have companion companionship with someone sex with someone That is the best opportunity for you to prove to yourself that you can be loved appreciated.