Emotional Addiction

A year ago someone at a local sports facility I go to started talking to me.  Initially I wasn’t interested.  We are both in relationships, but I thought we could be friends.
This person told me everything I wanted to hear and made feel totally fantastic and before I knew it I liked him back.  From what has happened over the year I think he is a narcissist and he intermittently love bombs me, but I can’t seem to get over it.  Pre-lock down we saw each other a lot at the local sports facility.  Nothing ever happened; we just hang out and both know we like each other more than we should, but I feel like this could be a game to him.

There seems to be a cycle and it feels very intense.
– get on really really well, have a great time
– I feel like when we are not together he doesn’t care, I constantly check if he’s messaged me on social media (these days it is extremely rare but I still keep checking)
– I get frustrated, we will argue because I feel that he doesn’t care about me
– we make up

Neither of us are leaving our partners so it is pointless but I can’t seem to stop myself from keep going back for more. I let him disrespect and objectify me (verbally) and I know that I shouldn’t let him do this, but I don’t actually mind that he does this and I am flattered rather than disgusted, then I feel shame because I feel like I should feel shame about him treating me like this.
I have so much guilt around the fact we both have loving partners, who have no idea about our relationship, even though it is not physical it’s still a betrayal.
I really want to break this destructive and intense cycle.  I’m constantly distracted and living in fantasy land.  Any advice would be great.