Some really excellent questions here. The last three posts have some good ideas of things to think about. Anniebrooke,perch, and thatquietgirl have some good insight into what the problems could be. good luck
Could it be related to the fact you are no longer on birth control? Are you guys using other forms of protection? Were you using said forms of protection while you were on birth control? It could be he's scared of getting you pregnant if you're not using other forms of protection or even if you are. If you weren't using condoms before but are now, it could be a difference in feeling.
Are you sure he is not masterbating? Does he have the opportunity to watch porn... porn can be addictive for guys he could be coming to that so is unable during intercourse? I do doubt he's gone 6 months without coming...
I wouldn't worry that it's you as it's a relatively new problem which he didn't used to have with you.
Most men like to orgasm, and if they are in the middle of 'the act' they feel very compelled to finish. It might indeed be about the relationship, about control or something passive-aggressive, or maybe a compulsive fear of you getting pregnant? Is he passive-aggressive in other ways?
Maybe it's the lord telling you not to have sex before marriage lol. Sounds like ur bf is just getting old. It happens