Got an Answer?
There are many different possibilities but certainly one that is common relates to the hormones generated during the first two years of a relationship which don't allow us to see the downsides to a new partner as strongly as we normally would. These hormones greatly increase the appeal of the new partner over the old partner who no longer generated these powerful hormones and basically makes it more likely that they think they've "found the one" or something along these lines, at least until the hormones die down.
Because they never really liked the first girlfriend, just holding on til something better came along.
Probably they realise the other woman wasn't the right one and the next person is the right one. Or they realise they f'd up and don't want it to happen again
Ok, so I'm a woman who has been in this situation in reverse.
I was with my ex for over two years, always thought he was a good guy, financially stable, no real negatives to him, just no real chemistry.
We discussed marriage and children as a down the road kind of plan, yet after 2 years it just didn't really seem like we were ready yet (despite being financially stable, both having good jobs, owning property etc).
We broke up and I married and was pregnant with my now husband within a year. We had much more chemistry and we just knew we would be together for ever (hopefully).
Can't really explain it, maybe chemistry?
Because they realise that they stuffed up with the first one and try harder with the next one not to lose them, read an article about it somewhere
I thought it might be because they realise they hate being without someone at all so are more willing to do what it takes to keep the next partner.
I think they get comfortable, probably aren't thinking long term, then one day their partner suggests commitment, or they just decide they are ready and realise the person they are with isn't the one. So they go off and meet someone else leaving the poor ex devastated. This is why I have no sympathy for men who string their partners along for years, then the partner accidentally gets pregnant.