It's annoying he looked at his phone during dinner. Who cares where it came from? You two should make a pact that both of you will turn off all electronic monitoring equipment when going out on dates. Ask him if he'd like it if you got a text from a ex boyfriend.

Other than that 'wicked...' summed it up above.

It gets worse after you're married. All these little things that bugged you then become mountains and worse of all its another woman - one that will be in your life for well over a decade. Meanwhile his first born will always be there and could easily be his favorite (yes every parent has a favorite - sorry Mom lied if she said differently)
and your kids will be second rate citizens and may even know it early one. (All kids figure it out eventually).

Just because someone had children before and they love their children doesn't make the experience better.

My dh has two DD from before me. SDs 15 & 17. We had our twin DDs3 and my dh constantly tells me how much better this experience is! He doesn't love his two older DDs any less but is actually enjoying it this time. First isn't always better or magical.

I too used to think of myself as "a mature, easy going, stable and easy to please woman" but becoming a step parent has driven me totally crazy at times. There are times when I feel like the old me and times when I don't recognize this ball of anger and hate and resentment that I become. One night I couldn't sleep and had a mini-break down. I stayed up all night crying, drinking and writing a really long post that I had intended to put on here about everything that upset me and where all this anger was coming from. In the end I didn't post it but just showed it to my husband instead. There were some pretty nasty stuff I said in there because I was feeling so low. He was very concerned about me and about our relationship after reading that. But I really think that it helped to clear the air and for him to see how everything was affecting me. For my part I am trying to adopt a more "zen" approach to being a step parent and not let things affect me so much and he is keeping BM out of my life. Lately things are getting easier for me, I haven't had any contact with BM for 3 months which has really helped, but it also means I dread seeing her again and know that the crazy woman in me isn't far away.

I'm relatively new to the step role but already know how it can change your personality drastically. So yes, step parenting had driven me crazy but I am hoping that it isn't a permanent state of being and working together with my husband we are trying to come back from there. I don't doubt that the crazy me may return again but at least I know that it won't last.

I would suggest that you talk to your boyfriend, write it down if you can't say it in person. Let him know how you feel, and then try to move on together from there trying to limit the intrusions into your life that trigger your negative emotions and trying to limit the effect they have on you when they do happen.