boyfriend problems

My sister just told me that my boyfriend of almost 7 years tried to kiss her last night( he missed she told him to fuck off) she also said he was acting weird cause he  keep saying fuck it a lot of times before he tried to kissher. So he obviously he wanted to kiss her. And before the whole thing happen she was showing text messages that he was asking her if she was still awake and was going to keep drinking. I feel so embarrassed he would do something like that know my sister trust him. But he clearly crossed the line. Is that consider cheating if his intention where actually to kiss her?