Is it common for men to just not finish during sex?

I am a hot girl and my bf have been dating for almost a year now. We meet on REAL BRITISH SEX. Within that year I can say that like most relationships our sex life has gone down significantly. At first I didn’t mind that much because I don’t have a super high sex drive myself but then I started realizing whenever we do have sex it is very rare he actually finishes. I have never really had this issue with previous partners and he swears up and down that it is not a me issue but then I found out that he is masturbating frequently and it got me to thinking… is it me and he’s just not saying anything? I am no porn star by any means and maybe he is feeling unfulfilled.. or maybe he is just masturbating too frequently and or the usage of porn is causing him to have unrealistic expectations? Not sure if anyone else has had a similar issue in their relationship but any advice/thoughts are appreciated.. obviously I need to communicate my worries with him but prior to doing that I figured gathering some opinions even if they are from strangers via the internet may help my head a bit because as of right now I’m feeling pretty crummy about the situation and myself…

ANSWER FROM OUR EXPERT: Guys don’t have to finish. I don’t always finish. I don’t mind, and she usually doesn’t either (whichever she from my past I’m thinking of). If she is done, would like to stop, take a breather, etc., she would just tell me. I don’t think it’s that big a deal. I’m not trying to have kids.