He no longer values the relationship in the same way that he used to.
This new job away as a pipeliner is really no excuse not to stay in regular contact with you.
He will not end the relationship while he is away because he wants to still have a sense of security in knowing that when he gets home, he will have you to come to.
However, he has become a lot less emotionally invested in this relationship.
You should contact him and let him know that you are ending the relationship.
If you wait until he gets home again so as to speak face to face, he will only make promises in order to keep you around.
These are promises that he will most likely not keep.
Once he goes away on another pipeliner job, he may respond to your texts and call you initially.
But, as time goes on, he will fall back into ignoring your messages and making excuses about why he was too busy to call.
He has continued to show his lack of emotional investment in this relationship in the way in which he avoids reading your messages on Facebook.
Again, it is best to contact him letting him know that you are ending the relationship.
It is time for you to move on.
The longer you wait, the harder it will be.