Larsa Pippen Parties Hard on Birthday Weekend with Boyfriend Jeff Coby

Larsa Pippen's partying her 51st birthday weekend away ... getting close with her man Jeff Coby at a Miami club -- and, their relationship sounds super serious.

The reality television star hit up E11EVEN -- a multilevel nightclub in the downtown area of The Magic City -- around 1 AM Thursday morning ... bringing a whole entourage with her.

Larsa started her night on the red carpet with some ladies and then with Jeff -- before hitting the dance floor for a few drinks, a little dancing and a whole lot of birthday well wishes.

Cameras were flashing all night capturing pics of the birthday girl ... who revealed to People that she and her boyfriend have talked about taking the next step in their relationship.

Larsa told the outlet she and Coby have discussed engagement rings ... not size, necessarily, but certainly the cut of the diamond -- revealing she likes brilliant cut and opal diamonds.

Pippen says she thinks she and Jeff are "on a really good path right now" ... so, don't be surprised if wedding bells are in their future.