Yes, it's possible to enact 180's and in some cases they are something we normally wouldn't do. Boundaries are hard, but you if you adhere to the ones that you set up and continue to repeat them over and over again, he'll get the message. If you don't enforce them, he'll continue to blow them off. For example, if you have dinner on the table, ready to eat, and he's hiding somewhere and texting the ow, you don't wait on him...you eat your dinner and put things away. If the two of you are to suppose to go somewhere and he's not ready, you go. If you don't want him texting or on the phone during dinner, ask him politely not to do so. If he continues to do it, get up and put the meal away. You do have some say in your home and he's running around like a spoiled 2 yr old testing to see just how far he can go.
If he doesn't put his dirty clothes in the hamper or leaves dirty dishes in the sink, don't do them for him. I know it'll drive you nuts, but you have to learn to look at him as a roommate and not your h. If you had a roommate, you wouldn't be picking up after them or doing things for them. You have to determine what boundaries you want to set and adhere to them. None of that wishy washy stuff or he'll know he can do whatever he wants and you'll do nothing about it.
Another 180 is to go out and do your own thing and not invite him along. Doing the opposite of what you've been doing will cause him to stop and take notice and in some cases, his curiosity will come out to play. Whatever changes you make in your life that make you happy, they have to become permanent. You don't make changes just to please him.
Well, he's already got the ow on his radar, which means she's his number one priority for right now. You can't be replaced because you are a very unique individual who has been w/him for quite some time. This ow is new and she doesn't know him the way that you do. It's a challenge for him and keeping things secret helps w/the euphoria right now. Yes, he may be doing things for her, but it's going to get old.
Generally the MLCer will hook up w/someone who has the same issues or someone who will look up to them as being their "savior". They tend to feed off of each other for a long period of time. Birds of feather flock together...but it will get old or one of them may find someone else. Time will tell.
It's important during his travel time that you take care of yourself. It's important that you do some fun things and learn to be more independent and have faith in the system. The advice you receive here does work...but you have to have faith and to try to stay positive.
Keep the focus on you and allow the man upstairs to work on your h.
Sit quietly, the answers will reveal themselves when you least expect them to. The past is gone, the present is a gift and you need to focus on today, allow the future to reveal itself when it is ready.