If your skin tears too easily when trying to stretch foreskin this is the telltale sign of a yeast infection. It may not necessarily be yeast infection but it most probably is. Yeast infection makes the skin thin so that it tears.
Mostly this can be cured by regularly cleaning off the inside and outside of your foreskin and glans. It is better to use an anti-fungal wash like Men’s intimate wash.
You can also use a clean cloth to clean off the foreskin and glans. Do it daily before going to bed.