He may be a good guy but if you are not matched on the values that are important for you, that is not 'monkey branching' and it is a valid reason.

You are very clear: "I don't want to marry my boyfriend and I don't see my future with him anymore". This is a major red flag.

So, would you rather stay in a relationship that does not fulfill you, so as not to disappoint someone else? Going along with the relationship because it is 'easy' will be a disservice to both you and him.

If this is not addressed now, this can lead to the breakdown of your relationship down the line, with a build up of resentment, anger or worse.