<human>: Give me the gist of the text in a nutshell

I am a cheater. Not in the physical sense - I don't actually cheat on my partners. But I want to. And it's been like this for as long as I've had romantic feelings for people.

It's like, no matter how wonderful my partner is, when I'm in a position where I'm mutually attracted to someone else, my relationship mentally fades away. This new person is all that matters to me, even if I only just met them.

When I was 15 or 16, I had two simultaneous, emotionally-invested, unofficial relationships, and even then I still had the desire and motive to flirt with other people. I don't know. I feel like there's something wrong with me, that I can so easily forget my partner and operate in a separate world where I seek sexual and emotional gratification.

The only reason I haven't physically cheated in my "adult" relationships is that I feel extreme, piercing, last minute guilt whenever it threatens to escalate physically. So I guess I have that going for me.

I would really appreciate any advice on this, including just telling me that this is serious enough to get my butt to a therapist. I appreciate any and all advice.
<bot>: I have difficultly not cheating on people, and I'd like to figure out some way to stop myself from even feeling the initial desire to do so.