Oh, Shelley, ((((((((HUGS))))))))
This must be very hard on you, and many have thoughts on this in various degrees.
Of course, you will change, not in the core as a person, but because you don't have the weight any more that was limiting your physical activities, and your thoughts in some things that you can/cannot do. So, how you EXPRESS WHO YOU ARE is going to change.
Remember, Craig went on to start singing and get his own band AFTER his weightloss, not before, even though being a big band singer was his dream since he was 4 years old.
It can be difficult for your partner, if he felt secure with you because he he saw and liked how you expressed yourself, and did not think to look at the person who you are in the core. You are turning out to seem to be a different person to him, and that may be pushing both him and you into new corners that can feel insecure.
If he isn't willing to talk about what both of you see/feel from both sides, or if he gets emotional when you try to talk this out, then maybe, it will be for the better if you consider getting outside/professional help.
Who knows, even if he thinks he doesn't like going out sometimes, he may find that once he takes the first step, he may find himself enjoying the time out on town more than he had exepected, because you are having fun with him.
That said, men are such clods

, it takes soooooo much

to get into their thick heads that having fun and enjoying the time with eachother in a scene that's away from home is a great depressor of daily stress, and a must for women, since often enough, the home scene is a place of work for women, as well as the office.
Make the choice that is best for YOU!