What Level of Misbehavior Constitutes Gross Misconduct

My question involves labor and employment law for the state of: I am a senior staff member and have recently entered into a relationship with a co-worker of a lower position. Other co-workers have found out about this and have been gossiping and spreading rumours within the workplace which have now reached the management team. I was then given the ultimatum of ending the relationship, leaving the company or her leaving the company. I decided to end the relationship but staff have proceeded to spread rumours so my manager has told me he has lost confidence in me.
Over the weekend an issue arose in work where the girl I was in the relationship with needed a lift home and approached me, which I then agreed to doing. Another manager used fellow employees to gain this information and has then informed the store manager.
I would like to know what my rights are in this situation as I may be facing losing my job. Is this gross misconduct?
Thank you in advance.

If you are referring to just being terminated, your employer can terminate you for any reason or no reason at all and this is a very good reason for booting you out the door and there wouldn't be a thing you can do about it.

If you are referring to collecting unemployment benefits, well, you didn't post your state in spite of being asked for it, so there's no way anybody can be specific about your state laws.

In general, however, since you've apparently disrupted your employer's business and were seen giving the woman a ride after being warned, this could very well rise to a level of misconduct that could disqualify you for unemployment benefits.

I suggest you start looking for another job ASAP.

In the future, avoid romantic relationships with co-workers.

There is no bright line that defines the difference between misconduct and gross misconduct, but it matters what your concern is. The two things, regarding the end of employment, where the definitions matter are with COBRA and unemployment.

COBRA can only be denied in cases of *gross* misconduct. While there is no specific legal definition, the rule of thumb I was always taught to use was, unless the misconduct reaches a level that someone could prosecute, it's not gross misconduct. For COBRA purposes, you did not committ gross misconduct as I have always been taught to define it.

For unemployment, there's a lot more grey. It doesn't have to be gross misconduct to disqualify you; it only has to be misconduct. It is the state, not the employer, who determines whether the misconduct reaches a level sufficient to deny unemployment. Unfortunately for you, a great deal of emphasis is placed on whether you knew or should have known that your conduct was displeasing to your employer. Since you had already, in effect, been told to stay away from her, taking her home (however innocently) might well be seen as sufficient misconduct to deny benefits. Only the state can say for sure, but while I can say with confidence that you will qualify for COBRA, I cannot say the same about unemployment.

If you are asking whether or not you can legally be fired over this, the answer is an unqualified yes.

OP is not in the US so these replies are probably not accurate.

OP where are you?