Separation or Divorce
It tends to be more and more normal for people who have been in a long term relationship or married to separate or get divorced.
If you have a will in place then unlike getting married, where an existing will is invalidated, getting divorced does not invalidate your existing will.
Instead, any specific gifts or gifts of residue that you made to your former spouse will fail as if your former spouse died on the same day as your decree absolute was made.
These failed gifts will either be gifted to the remaining beneficiaries, or if the will does not allow that to happen, the failed gifts may create what is known as a “partial intestacy” where the failed gifts are not dealt with through your will, but by applying the intestacy laws.
If you are not married but break up with your partner who benefits from your will, then unless you change or destroy your current will when you die your ex-partner will benefit as if you were still together, even though you are not, and may have even moved onto a new relationship.
If you are still married, but separated, under English law your estranged spouse will still receive everything gifted under your will as if you were still together and happily married.