ET's Katie Krause spoke to Lee at Variety's Power of Young Hollywood gala on Tuesday night at The H Club in Los Angeles, where he expressed his sadness over Jenner and Carter's breakup after five years together. The two announced their split on Friday.
"It's just tough, you know?" Lee says. "It's tough because I'm close with both of them and they really do love each other. I mean ... they were such a great couple and it's always sad seeing a couple like that split up, but you know, as everyone sees they're being very amicable about it and I don't really think there's any bad blood. It's tough. It makes me sad, to be honest."
Although Jenner and Carter had a wedding ceremony in Bali in June 2018, a source close to the couple later told ET that the two were actually never legally married. Lee calls the situation "complicated."
"I think signing a piece of paper doesn't necessarily -- like, you may legally be married to somebody but, you know, I think as long as ... I don't know it's more of an understanding," he muses. "If you love a person and you think they're your soulmate ... y'all are married! You know, you've been together five years. Like, it's devastating to see them split up, but you know, obviously I support them both in whatever they want to do do and I'll be the same moving forward with either one of them."
He also acknowledges that their MTV reality show may not have helped the relationship. During this season of The Hills: New Beginnings, problems between Jenner and Carter are obvious -- a big one being Carter wanting to settle down and have children and Jenner not wanting the same things.
"I think in the beginning of the show there's definitely a little bit of tension between them," Lee acknowledges. "It's hard to see that when you're with somebody, it's hard to see when you're with a person or in a relationship. ... what it's like from an outside perspective to people looking on. Sometimes that outside perspective can look toxic even if you don't realize it. So I think more than anything, I think watching it may not have helped."
Still, Lee also doesn't rule out the possibility of Jenner and Carter getting back together.
"I just hope they can be friends ... first," Lee says. "You know, and if they can be friends, hopefully, down the road maybe they'll figure it out."
Jenner and Carter announced their breakup with a joint statement from their reps reading, "Brody Jenner and Kaitlynn Carter have decided to amicably separate. They love and respect one another, and know that this is the best decision for their relationship moving forward." A source told ET that Jenner and Carter -- who began dating in 2014 and got engaged during a trip to Sumba in 2016 -- had been having problems for some time.
"Not having my dad at the wedding, it was a bummer," he said. "Honestly, it really did hurt and I would have loved to have her there, but she had better things to do. Apparently."
"My dad and I have never really had a great relationship," he added, before praising his mom, Linda Thompson, for all her hard work and dedication to the family. "Through all the ups and downs that my family has had, my mom has always been the rock."