Since becoming pregnant, my wife doesn't seem to care much about me: how do I stop this?

Theres really nothing you can do to change the way shes acting. You can only try to be happy with what you have. She should start feeling a little better around week 16. So just hang in there. She's probably too busy thinking about the baby & doesn't realize the decrease in affection that she's giving you. While she is pregnant it would be a good idea to ask her about whats going on with the baby and look up things with her & talk to the belly. Bonding with your soon-to-be child together is a good way to bond with each other and feel closer not only as parents but as a couple and a family. Dont put so much pressure on yourself. I'm sure your body isn't the problem. As for getting out of the house, she knows she wont be able to do much once she gets bigger or after the babys born, so its a good thing to get out right now.