Im glad you feel this is a place where you can vent your feelings im not trying to talk you out of how you feel but you don't know what will happen in life, please don't close yourself to the idea of love as i think you would be denying yourself - not to mention someone else - a wonderful oppertunity. This is how ive interpreted your points, feel free to read on if you wish

1. Yes this girl was unique - but so is every other woman. I think the chances of no other person being able to make you feel happy is extremely unlikely.

2. Yes relationships can harbor pain but i think good communication and a willingness to try and resolve issues as best as possible when they come along can help this. The way i see it is, without pain it would be pretty difficult to appreciate the good things in relationships - the same could be said for life itself.

3. I think most people in long term relationships would own up to a bit of flirting - im in no way condoning it or saying its normal but its certainly not unusual so you aren't alone in this experience and as long as its nothing serious or happens frequently i think this is something you have to try and come to terms with. As for lying and dishonesty, we all do it. If these are small infrquent white lies that have no real bearing on the relationship i wouldn't worry. Again its a communication issue but be glad that you have this much integrity - its a quality highly sought after.

4. If she isn't in love with you then no she wouldn't be struggling as much as you are - i think love will mean different things for different people but it does exist, there are many people in happy relationships to prove that it is out there.

5. People are not defined by their relationships - they have a life outside of being with someone and i think its perfectly acceptable for partners to want to meet up with their friends occasionally and dedicate their time to other stuff. If you are not happy with certain things in a relationship you have a right to say so - whether the person is understanding enough to discuss the issue is another matter but most couples i encounter are as accomodating and respectful as they can be. Again i think the right person and right circumstances make all the difference.

The fact of the matter is - not everyone finds someone to share their life with. Yes this is sad but it doesn't mean life can't be just as fulfilling - i think in time you will move on from this girl. Be glad that now you better understand what your expectations are and what you want to avoid in future relationships. I think its rare people find someone who is 100% what they want - we all have our flaws and imperfections its whether or not there is enough about the person to love and admire that makes all the difference. Im sorry if ive not been helpful. Please be kind and patient with yourself during this time. Break ups are hard but its not impossible to move on from them. I hope theres enough other stuff in your life which you enjoy and can help you through such a difficult time. All the best.