db={users:[{_id:"abc",name:"abc",group:1,location:{type:"Point",coordinates:[53.23,67.12]},calculatedDist:112},{_id:"xyz",name:"xyyy",group:1,location:{type:"Point",coordinates:[54.23,67.12]},calculatedDist:13},{_id:"123",name:"yyy",group:1,location:{type:"Point",coordinates:[54.23,67.12]},calculatedDist:13},{_id:"rrr",name:"tttt",group:1,location:{type:"Point",coordinates:[51.23,64.12]},calculatedDist:14},{_id:"mmm",name:"mmmm",group:1,location:{type:"Point",coordinates:[51.23,64.12]},calculatedDist:14},{_id:"eee",name:"uuu",group:1,location:{type:"Point",coordinates:[55.23,62.12]},calculatedDist:143}],partnership:[{_id:"xyz_rrr",users:["xyz","rrr"]},{_id:"rrr_eee",users:["rrr","eee"]},{_id:"eee_rrr",users:["eee","rrr"]},]}

db.partnership.aggregate([{$match:{$expr:{$eq:[{$last:"$users"},"rrr"]}}},{$lookup:{from:"partnership",let:{likes:{$last:"$users"},me:{$first:"$users"}},pipeline:[{$match:{$expr:{$and:[{$eq:[{$last:"$users"},"$$me"]},{$eq:[{$first:"$users"},"$$likes"]}]}}}],as:"paired"}},{$match:{"paired.0":{$exists:false}}},{$project:{_id:0,user:{$first:"$users"}}},{$lookup:{from:"users",localField:"user",foreignField:"_id",as:"user"}},{$project:{user:{$first:"$user"}}},{$replaceRoot:{newRoot:"$user"}}])