In order to answer your question thoroughly, it’s important to understand precisely how Colorado law defines trespassing. Trespassing occurs when someone unlawfully enters or remains on another person’s property or within another person’s dwelling without expressed permission to be there. 

In eviction cases, once the judge orders the sheriff to remove the tenant and their belongings from the premises, the evicted tenant risks first or second-degree criminal trespass charges if they return. The severity of the charges depends on factors such as whether anyone was home at the time of the trespass and the extent of the trespass. Thus, by returning to the property, you risk receiving anything from a petty offense to a felony charge. C.R.S. 18-4-502; C.R.S. 18-4-503

So even if your boyfriend is an authorized resident of the property and dwelling, so long as he is a renter, accepting his invitation puts you at legal risk. It is ultimately up to the property owner to grant or restrict access to individuals. Therefore, I would advise against returning to the property and suggest establishing another meeting place for you and your boyfriend.