Falling for someone, whilst with someone else

Hi girls,

I know this is a horrible situation and I hate myself for it, but recently I have started speaking to someone I used to have a ‘thing’ with.

Every party, night out etc we would end up together (never slept together tho)

My current partner, we’ve had a lot of shit happen and I’m unhappy. I love him but I am so fed up of the same old behaviours, I can’t ever see him changing, because 5 years on at the age of 27, he would’ve by now, right?

I just don’t feel content with him anymore and I’ve tried telling him but he just makes me feel bad and I don’t know what to do.

I have tried thinking no you don’t like this other man, it’s just lust but I find myself genuinely smiling/laughing at messages and I just feel like he has such a good impression on me

What do I do girls? I know some of you will give me a hard time