Struggles Surrounding Forgiveness

In my experience of ministry, there are four particular problems with forgiveness -- in the sense that they present real spiritual struggles for people: 1. A sin is still going on -- say adultery or theft. Should I forgive? 2. The person will not apologise -- they may even be in-my-face about it. Should I forgive? 3. The offender may not know what I am forgiving them for -- or they may not know what they did to me -- unaware of the pain, or unaware of what they initiated. Should they know first? And 4. What if forgiveness should cause complications for a third party? The offender becomes a repeat offender, or a bad attitude causes others grief. Should I have addressed it? OBSERVATION: There are questions besides. I'll leave these questions as questions -- at least for now.