Question about forgiveness

I'll start off by saying that don't get me wrong, I love Christ. And I'm not asking this question trying to find a loophole in the bible or way of living through Jesus, rather I'm curious to the answer since I can't really find it. In Matthew 6:15, it says "But if you do not forgive others their trespasses, neither will your Father forgive your trespasses.” For me that means that I should forgive others for their wrongdoings to me, despite if they've never asked for forgiveness or apologized. I guess the reason Christ tells us to do this is to also free ourselves from longing hatred or bitterness towards a person, not so we can easily let people manipulate us by always forgiving them. We can forgive them but also stop associating with them for our own good as far as I know. But here comes the actual question. In Luke 13:3 it says – “But unless you repent, you will all likewise perish." Maybe I'm treating this too literally, but how come the Lord wants us to forgive others despite them not asking us for forgiveness or repenting, but if we don't ask for forgiveness to the Lord we won't enter heaven?