Some people wake up one day and recognize their life is not what it should be. They might suddenly see the truth friends and family have been saying, and they tell their long time partner to fulfill their commitment or they will leave. This person must be willing to see their relationship end because it is seldom that a person with commitment issues will be able to go through with the promises they have made.
When a relationship of this nature ends, it is seldom a time when people become angry or end up as enemies. Both people in this type of relationship have been living the same life for years, and it is more of a realization for one person that their partner cannot change. They break up, but the uncommitted person is convinced their partner will come back because they have been there for years. The partner who leaves realizes they have simply been living a suspended life, and they are too busy exploring new possibilities to care about their former partner.
If a dating situation has been going on for years without advancing, it is a good move to make a partner fulfill their promised commitment or leave them. The person may realize they have to do what they have promised, and this might change their attitude. If they do not change their ways, it allows the other person a chance to move on in life with no feelings of guilt or regret.
Leaving a long term relationship is difficult because of the comfort it brings to both people. They have had a partner who appeared to be there for them, but that is not always a good sign. Leaving gives a person the ability to see they have been managing their own life for years without real help, and they can now live a better life without the drag of a person who would not make a real commitment.