Most Helpful Guy
it depends on series of events happend in past of bf/gf,
and most imp is to understand that when you proposed him or her, he or she was already broken and recently gave up on relation, so you are not just telling him or her your feelings but also you are conveincing him or her that you will help in healing the wounds.
because no matter how bad your relation was, *if you was really in love*, there will always be soft corner for ex in heart, and forever you will have feelings for that person, even if you stay strong publicaly.
and this must be accepted that feeling can not be vanished in few days or with new relation.
and if you love your partner, thn wait for a while, discuss and understand his or her point of view and why he or she is still attracted to ex. coz this attraction only means one things.. and that it is you who js not upto the expectation of person, you are failling to replace the person.