Recognise that it's never easy
Understand that there is no pain-free way to break up. We all wish that we could end relationships without any hurt or pain. But no matter how broken the relationship is, officially ending it will cause pain on both sides. Once you acknowledge that there will be pain, you can be prepared for the aftermath.
Do it face-to-face
Your partner deserves the dignity of a face-to-face conversation. An intimate setting is arguably better, but if you are worried about your partner having a violent reaction, a public place is safer.
Be honest but don't give too much detail
In general, people want to know why they're being dumped. While ‘you're terrible in bed' or ‘you lack ambition' might seem like an honest answer, it doesn't really preserve your partner's self-esteem or dignity. Using a reflexive sentence like ‘I don't think our long-term goals align anymore' are nicer ways to express your feelings. Don't do a play-by-play of the things the other person did wrong or use clichés like ‘it's not you, it's me.'
Do not give in to arguments or protests
If the breakup is a surprise for the other person, they might try to argue, protest, or give reasons why you should remain together and try again one more time. If you are at the point of breaking up, nothing can restore or revive the relationship now. Giving in will only delay the inevitable.
Show sympathy
Express your sadness at the breakup and share some good things about your time together. Being dumped feels really bad. You can soften the blow a little by talking about some of the good times you shared together.
Avoid blaming or shaming
Avoid turning the other person into ‘the bad guy'. Nobody's perfect. You have faults too, and turning your ex-partner into an evil figure is not helpful (aside from obvious instances of violence, but that's not the kind of relationship we're talking about here).
Give yourself time to grieve
Even if you are the one ending the relationship, there will be a period of heartbreak, sadness, and pain. This is one of the most difficult parts of figuring out how to break up with someone you love. You still care about them, but you need to remind yourself of the reasons why the relationship isn't working.