

Couple of reasons in my experience. Cigarettes have a generous butt, and are pretty structurally sound, which makes them pretty easy to handle that way, and you can ash with a simple flick of your thumb. Joints often have no butt, or just some folded up but of paper or some other dodgy bullshit, so there’s far less to grab onto. They’re also often pretty flimsy, and fall apart easily. So holding them that way gives you better control and is more gentle on the joint.
In what way is he your boyfriend? He doesn’t sound like he is. Poly is really hard, and it’s full of shitty people who use it as a justification for being shitty. Sounds like you need to do a whole bunch of work on yourself right now, and it doesn’t really sound like either of your “partners” are good for you.