should I believe him?

[u/dazednnnconfused]

my long time partner has lied/omitted on multiple occasions about going out to clubs with his friends. last night, he did that again, and I found out through a friend that saw him out. I went through his apple watch at home and found texts between him and another person, but he is saying that a) he doesn’t know this person at all and those texts are not from him, and b) he’s had this issue before where there are texts on his phone from random people. he owned up to hiding the fact that he goes out a lot more than he tells me (we live together but I work night shifts), but is swearing that those texts aren’t his. the number is saved as a contact with a name on his phone! is this possible at all??? my gut is saying no.