Bradley Cooper "seems more protective" of Irina Shayk since she has fallen pregnant.
The 30-year-old model is reportedly expecting her first child with the Hollywood actor and Bradley, 41, has apparently become even more chivalrous towards his girlfriend in recent weeks.
A source said: "He has been spotted dropping her off at the airport with kisses as she is about to take off for another job. They are just a very sweet couple."
Bradley and Irina have been dating since May 2015 and are said to be as happy as ever.
A source told People: "Bradley and Irina both seem very independent and supportive of each other's careers."
Irina - who previously dated soccer star Cristiano Ronaldo - is also said to have grown close to Bradley's family and vice versa.
The model has developed an especially good relationship with Bradley's mother, who lives with her superstar son.
The insider explained: "They also are very close with their families. After Bradley's dad passed away [in 2011], his mom Gloria mostly lives with Bradley in L.A."
In fact, Irina and Gloria often spend time together when Bradley is not around.
The source shared: "Irina was quickly introduced to Gloria and the two seem to get along great. They even spend time without Bradley. They take walks, go shopping or share long lunches."
Irina - who has yet to confirm her pregnancy - recently revealed she wants children sooner rather than later.
She explained: "I think family is the reason why we are here. I love my job and it's very important to me. I really enjoy what I'm doing but it's not the most important thing in my life - family is, friends, people who I love.
"My father was married to my mother for more than 20 years and, yes, definitely one day I want to have a family because that is the most important thing on this earth. I don't think there is a perfect time. I think it's more important to have the right person by your side.
"My sister had her baby when she was 22, and for her that was the perfect time. I will be 31 in January, so maybe soon it will be my perfect time. I don't know - time will tell."
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