Why men leave long-term relationships and marry women they just met

Since men are the ones who take the relationship to the next level, i.e., marriage, there are situations where men leave their long-term partners and marry someone who they just met.
Why men leave long-term relationships and marry women they just met
The reasons are often complex and generalizations might not cover the ground. However, potential reasons for a man to leave a long-term relationship for a new one include:

They’ve found what they actually want
People often find themselves in relationships or situations with individuals they don’t particularly like.

However, they might tolerate these people due to other positive qualities or circumstances.

Meeting someone new can lead to a sudden realisation that they have found what they’re looking for, prompting them to pursue that relationship instead.

Emotional disconnect
It’s possible to become disconnected from your long-term partner. If a man feels emotionally distant from his long-term partner, he may be more inclined to marry someone with whom he feels a stronger emotional connection.
Boredom
When the sparks in a relationship wane, it can become boring and tiring. Some men may seek change or excitement; a new relationship is an opportunity to start over or try something new that makes their heart racing and makes them feel alive.
Unmet expectations and unresolved issues
A man may quit a long-term relationship if it fails to meet his expectations or needs; he may have matured and changed, requiring something other than what his current partner provides.

Unresolved concerns in a long-term relationship can build up animosity, and as a result, people seek refuge in other relationships where these issues are less evident.
Better chemistry
Chemistry or an overpowering connection with someone new can often outweigh the familiarity of a long-term relationship; this may lead a man to decide on someone to whom he feels more attracted, at peace, and with whom there is a better synchrony.
It’s much better to have a failed relationship than a failed marriage; if someone is hesitant to make a big commitment like marriage, forcing it to happen will only lead to pain further down the road.