"We carefully assessed the complaints we received about this series of Love Island," a spokesperson said.
"We recognise that emotionally charged or confrontational scenes can upset some viewers.
"But, in our view, negative behaviour in the villa was not shown in a positive light, and contestants were seen supporting or apologising to each other.
"We also took into account that the format of this reality show is well-established, and viewers would expect to see highs and lows as relationships and friendships are tested."
The total number of complaints is higher than the 3,500 in 2024, and is the highest for a summer series since 2021, when 36,000 complaints were submitted.
Other issues to attract complaints this year included Dejon Noel-Williams' behaviour towards Megan Moore, while some viewers accused producers of manipulating islanders' emotions and using biased editing, including allegations of racism in the portrayal of Shakira.
In response, ITV said: "We would take any suggestion that any editorial decisions are made based on race very seriously indeed and would refute this in the strongest possible terms."
Some viewers complained about a decision to bring back Megan Forte Clarke after she was dumped from the villa. ITV's terms say producers have the discretion to "reintroduce an Islander seen in earlier stages of the competition who was previously evicted".
ITV also says participants get training in advance about "mutually respectful behaviour in relationships" and "behaviour patterns associated with controlling and coercive behaviour".
And they get "comprehensive psychological support" and an aftercare package including "support to all Islanders following their participation on the show".
Toni Laites and Cach Mercer were crowned the winners of this year's summer series at the start of August.
