Always, every time.
Other people are our mirrors. This is the divine purpose to relationships ~ to show us the unhealed aspects of ourselves which we wouldn't uncover sitting by ourselves, where there is no outside stimuli to prompt the trigger.
Every person you meet is your spiritual teacher, inviting you deeper into yourself. Are you taking up the invitation?
Or are you deflecting this opportunity to learn and judging, criticising, shaming and blaming others, making them 'wrong'?
Wrong and right do not exist on a universal level. There are things that support joy and things that amplify suffering which we have each created unique moral codes around - laws, religions and philosophies are generally centred around not hurting others (or this was the original intention before these systems got distorted).
But if we go around judging others (or ourselves!) as wrong, we amplify the suffering on the planet.
We can lovingly recognise and point out when someone's actions hurt us or others (we always get to honour our boundaries and say no to unhealthy behaviours) and our job is also to work out what the trigger is here to teach us.
For example maybe your partner taking space triggers you ~ you are being called to learn how to self soothe and heal your abandonment trauma.
Or if someone being angry at you triggers you, maybe you are being called to heal shame and make peace with not being able to please others all of the time - learning to love and embody your authentic self always.
Once you realise relationships are not here to make you happy (meet all your ego's needs) but to make you conscious, you move from victimhood to empowerment. (Naturally we deserve to uphold our standards of respect and kindness - if a person isn't able to connect with love, they aren't a match to the gift of your presence).
Of course, sometimes triggers are warning signs from our intuition showing us when someone's energy is of a low vibration. If a person is abusive physically or emotionally, the trigger can be simply saying this is dangerous or unsupportive of my spiritual growth, so it's time to walk away. The lesson in the trigger is for us to love ourselves so much we never choose to accept poor treatment.
If it's not an abusive situation but you are triggering each other intensely or your needs are not lining up at this time, the trigger might invite you to take a time out (whilst also going within and figuring out what your needs and fears are and doing some self healing).
The trigger is always about us in the sense that we have a lesson to learn from it and we are called to respond consciously, but others projecting negativity upon us is not about us - when we trigger them, that's about their wounding. it's not our fault or a reflection on us what they say: e.g. if someone calls you selfish that doesn't make you selfish - it's a call for you to know yourself more deeply and find out what your integrity is calling you to do in that moment.
Each trigger is a deeper invitation into love.