Copied this from one of the very old pinned posts, can't take credit for it....
10 Steps to Distancing
1) Stop asking new personal things of your partner about him/herself.
2) Don’t give out personal things about yourself to them.
3) Don’t bend over backwards to celebrate any occasions that involve them.
4) Don’t bend over backwards to help them more than is necessary
5) Don’t help them if they or someone else can.
6) Avoid discussions that involve their lives, re: old topics.
7) Start to develop new activities that don’t involve them.
8) Try to make new friends, acquaintances, anything.
9) Make small changes in your life: rearrange furniture, change decorations, try new soaps, ride your bike in a different route, eat at a different restaurant, eat different foods, cook them a different way, shop at different stores, rearrange the landscaping, change some of your habits, change the style of clothing you wear, etc.
10) If they ask favors of you, tell them you want time to think about it.