Jessica Simpson Says She and Eric Johnson 'Learn from Each Other So Much': 'Our Love Is Only Deepening'

Jessica Simpson is lucky in love with husband Eric Johnson.

While chatting with PEOPLE about her partnership with Flonase, the singer and fashion designer, 41, also opens up about married life to Johnson, 42, with whom she shares three children — daughters Maxwell Drew, 9, and Birdie Mae, 3, plus son Ace Knute, 8.

Playfully teasing that she will "lose count" of anniversaries and other monumental moments within her relationship to Johnson as the years go by, Simpson tells PEOPLE, however, "I feel like every moment with us, we're growing as long as we're communicating, and our love is only deepening."

"I feel like Eric and I learn from each other so much," she continues, adding: "I feel like we're stronger than ever now, [more] than we were even at the beginning."

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Simpson and Johnson met back in 2010 when a mutual friend invited Johnson to a party. The couple then went on to tie the knot in July 2014.

Continuing to speak with PEOPLE, Simpson says that her own relationship — and how in love she is — makes her question other couples who aren't willing to learn and grow with one another.

"If you're in a relationship and it feels like it can't ever reach a deeper or a more connected level, I don't know," she says. "I just feel like [Eric and I are] somehow always sinking into something deeper and better."

"[If you're with somebody] that doesn't make you feel heard or safe or put you on a pedestal, or just honored in a way, it's not worth it. If you can't be authentically yourself while you're madly in love with somebody, you're not in the right relationship," the mother of three adds. "It's not serving you at all, or the other person, and it's selfish."

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Having three children, Simpson also notes, affects her relationship with her husband day in and day out. "Raising kids together, that's powerful. You're creating these amazing humans," she shares.

Still, the Dukes of Hazzard star says Johnson can grow frustrated when it comes to raising siblings — given that he is an only child — so Simpson says that she reminds her husband to "just go with the flow."

"It's about communicating and loving somebody," Simpson explains. "We both have the same purpose and the same heart in what we're doing together. And that's important."

"If you have different goals, that just takes you apart. And your kids will feel it ... they can feel tension," she adds. "A lot of times, they won't talk about it, but as a child, that's when you start to create insecurities, or know what a relationship is, how to treat people. They're watching."

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Simpson says that her husband overall is "such a good dad and a good man," adding that he is a "positive light in our family and encourages me to stay in the moment."

One important way the couple bonds together, Simpson says, is through their shared love of exercise, which helps keep their bodies — and their relationship — healthy.

"For Eric and I, it's so good to walk, because we're creative on walks and we talk through things," she says. "And you're walking through it. It's a really inspiring conversation.

"That's good for our relationship, and that's cardio," the Jessica Simpson Collection founder adds with a laugh.