Some friendships aren't built to last, and in the case of Brandi Glanville and Lisa Vanderpump from The Real Housewives of Beverly Hills, this is undoubtedly true. The pair's budding friendship started strong, but there were signs it wasn't forever throughout. Their personalities clashed in more ways than one.

Brandi entered the cast of RHOBH as a full-time housewife at the start of season 3. She was an outspoken addition to the cast, causing trouble, especially with sisters Kim and Kyle Richards, from the get-go. Lisa saw something in Brandi that made her feel maternal, and so an interesting new friendship developed.

Related: Why RHOBH Fans Don't Want Brandi Glanville To Return

From the moment their friendship began, it was clear to fans that Lisa found many aspects of Brandi likable and found other parts of her inappropriate and unacceptable. She took Brandi under her wing, almost like a mother, and at one time, Brandi even referred to Lisa and her husband Ken Todd as “pseudo-parents.” Many times throughout their friendship, Lisa would struggle to side with Brandi if she did or said something inappropriate, but for the most part, Lisa wanted to be there for Brandi, and Brandi felt the same way. A few moments throughout RHOBH, driven by two clashing personalities, defined how this ill-fated friendship would end up.

Season 3 Finale of RHOBH with Brandi and Lisa Vanderpump

During RHOBH season 4, Brandi was confronted and hurt when the woman, who her ex-husband Eddie Cibrian had an affair with, was also one of Lisa's employees, Scheana Shay, and was working at an event the cast attended. Brandi tried to get Lisa to choose between her and Scheana, and Lisa arranged for the two to meet up and hash out the issue. This was perhaps the beginning of the end as Lisa began to see a side of Brandi she didn't like. One example is during their cast trip to Puerto Rico when Brandi told Kyle that Lisa wanted to purposely pack tabloids featuring a story about Kyle's husband Mauricio Umansky allegedly cheating on her.

By RHOBH season 5, their friendship was looking quite bleak for the pair. While they both had said things about the other, neither was jumping to apologize. Lisa is known for her inability to say sorry when she's caught, so naturally, when Brandi wanted an apology from her, Lisa felt she didn't need to deliver one. During their cast trip to Amsterdam, Brandi playfully slapped Lisa and spent the remainder of her time there trying to get back in Lisa's good graces but making many failed attempts along the way.

Although RHOBH's Lisa and Brandi had a similar sense of humor, they were no match for each other. The friendship started strong and almost simulated a mother and daughter relationship, as Lisa tried to take former RHOBH villain Brandi under her wing and care for her. But eventually, their personalities clashed, and things happened between them that is now unfixable.

Next: RHOBH: Brandi Glanville's Plastic Surgery Transformation In Photos

The Real Housewives of Beverly Hills airs Wednesdays at 8 p.m. EST on Bravo.