IMHO, its not good to live a life full of regrets; you should move on with your life, accept that you can't change the past, and be happy with the present- regrets are not that much different from guilt. People feel guilty when they know they have done something wrong- guilt exists for a good reason, the purpose of guilt though is to address why you feel guilty though and either correct what wrongs have been done if you can, or accept that what done is done and move on.
You cannot let regret rule your life just as much as there needs to be a point where you need to stop dwelling on past issues. If there are things that make you feel happy in the present, then dwell on these and appreciate them and ensure you continue to have good things in your life, rather than dwell on the things which you cannot change in the past; if you dwell too much on the past, good things in the present may pass you by without you really acknowledging, appreciating or even noticing them. The main thing is what you do in the present, because this will affect what your future is like.
Time is a great healer- but healing needs to come from your part too. Be compassionate and tolerant to others, show kindness whenever possible, spend quality time with your friends and family, work well, make time for yourself in your life but also those that matter to you, spend wisely, eat and live healthily and try and help those in need when you can, try and see things from other people's perspectives, accept that you cannot change everyone else but also accept that you can change yourself if you put your mind to it etc- if you do these things, you will find your life will be filled with less and less regrets.
Relationships...Are important. People concentrate a lot on their relationship with their lover (or concentrate on finding a lover and having a relationship with them), but this isn't the only type of relationship that you should prioritize- all relationships are important, whether they are with friends, family, colleagues etc. Treat everyone fairly and with consideration etc- none of us are perfect.
Youth is the shortest part of life, so enjoy it and try to do things meaningful with your youth, create good memories and meaningful happy relationships with other people, give yourself credit and be happy with yourself

. Deal with problems, not dwell on them. Don't let your past decide your future- you need to take your own life in your own hands and decide what you want to do with it and what you want out of it, you are your own ruler, not others and not your past

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