I've (28f) been with my partner (28m) for a year and a half now. We have a great relationship, very loving and supportive.

Recently I've been having intrusive jealous thoughts, torturing myself thinking he's cheating on me or would prefer to be with someone else; sometimes these are about one person in particular, other times just like a random person. I've NEVER dealt with feelings of jealousy before, I've been in open, poly and long distance relationships, never been cheated on and never felt jealousy.

I am aware my mental health is taking a big dip right now, and I've been feeling pretty lonely and isolated, which absolutely are contributing to these thoughts. I just want some advice on how to deal with them?

I know this is a me problem, absolutely nothing in my partner's behaviour that should make me doubt him. He's just a lot more social than me, has a lot more friends and coworkers, and I feel is more attractive and just better than me overall. He's nothing but loving and supportive and patient towards me. I know this is my head torturing me, so how do I work through this and out the other side? Active advice and things I can do to work through these thoughts and conquer them?