Someone perfectly nice might not be right for you for a lot of reasons. For example: some people doesn't want long distance relationships. So you might meet someone "perfect" but that lives 500 km from you and decide that you can't have a relationship because neither of you wants to move to another city/country. Or you can have different ideas about children. Or simply want different kinds of lives.

People need to understand that a rejection doesn't necesarily mean that you think that there is something wrong withthe other person. Most of the time only means that you think the relationship won't work for whatever reason.

People have families, friends, dreams and lives and I think it is unhealthy to think that they must be willing to renounce on all that just to try at a relationship.