To calculate the time you've been together from July 23rd to December 13th:
- From July 23 to July 31: 8 days (31 - 23)
- August: 31 days
- September: 30 days
- October: 31 days
- November: 30 days
- From December 1 to December 13: 13 days
Now, add them all together:
- 8 days (July)
- 31 days (August)
- 30 days (September)
- 31 days (October)
- 30 days (November)
- 13 days (December)
Total: 8 + 31 + 30 + 31 + 30 + 13 = 143 days
So, you and your boyfriend have been together for 143 days as of December 13th.