NSEs are non-consensual sexual experiences (e.g., sexual abuse, assault and rape). The term NSE is sometimes used in scientific literature as an umbrella term in order to describe a broad range of experiences.
Some people who have endured NSEs feel uncomfortable using terms like assault or rape to describe what happened to them, often because they don't feel that their experience measures up to these serious offences. It's crucial to understand that there isn't a hierarchy of NSEs where getting violently raped by a stranger is more real than getting non-violently raped by a partner - if you had a sexual experience of any kind that you did not consent to, it is real and you were violated.
There are many examples of non-consensual sexual experiences that some find difficult to relate to more obvious forms of assault and rape. For example, when a person is so intoxicated that they are unable to give meaningful consent and unwanted sexual activity occurs - they often have a difficult time understanding the experience in terms of assault or rape.
Another common example is when the abuser/rapist is the spouse or partner of the victim - although women are more likely to be raped by someone they know than a stranger, that there was prior consensual intimacy with this person can make it harder to understand or accept that a violation has occurred. This is likely in part due to societies mishandling of the concepts of consent and sexual agency, and certainly the culture of victim blaming. Many victims feel extreme guilt and shame for what has happened to them and have a very difficult time seeing themselves as victims. This is also often the case also in scenarios where the victim is male and very much so when the aggressor is female.
I think it's important to allow everyone the right to define what happened to them whatever they like. If you had a sexual experience that was non-consensual you absolutely should define it in whichever way you are comfortable with and whichever way facilitates your recovery.
However, it's also important that victims aren't compelled to downplay their experience simply because they don't think it measures up to more violent or clear-cut cases of assault and rape.
Victims should also access all the help and resources that they need and deserve to help them recover from the trauma. The psychological effects of assault and rape vary across individuals and do not necessarily correlate with the percieved 'severity' of the experience.