Do most people generally lie about their happiness in a new relationship to make an ex jealous and want them back and how can you tell when this happens?

Answer 1

As a general rule they are not lieing. There is the flattery of knowing someone finds them attractive and interesting. Meeting their friends and being shown off, going new places etc. These things are exciting and make that person happy. However that all starts to change when the "new" starts wearing off the relationship. Unless they do something totally stupid and get married before they actually know the other person well enough, they usually find that their "new" 'other is not as wonderful as they thaught at the first.