I have a deep, intimate relationship with somebody I met online 3 years ago. They are polyamorous, and our current relationship is best described as...casual love? No meeting the parents or labels but yes we call each other pet names type-deal. It's worked out fine, and I've felt very secure with our dynamic. This was until they moved in with a friend to do adult content together. Just them two, a pair. They claim it's not romantic, and is for business convenience, but I find it very hard to picture him not falling for her seeing as they now spend every day together. It was so hard to hold in those feelings about the threat of gradually losing him, and I exploded as soon as I found out. I crossed boundaries &amp; I fought him at every turn and demanded he find a different roommate. I insulted her endlessly and cruelly. I would try to be "cool" for a day or two but would just blow up once he took "too long" to answer my messages then in which that time I'd just imagine all the fun and love they were having together. Eventually, he had enough of my flipping and he said to talk to him in time, and with "proof of improvement" in my behavior &amp; to leave him alone for the time being. I'm now just accepting my illness and trying attempting to teach myself the tenets of DBT.  I can't stand to loose this person, I can't. I don't want to bother them while we are break, but I want them to know that I am trying.  I'm thinking of reaching out at the 3 week mark to give them the option of slowly trusting me again with the assurance I am going to rely on my coping and regulation skills...any advice appreciated.