Hey guys. I'm a female and I need advice

So my partner and I have been arguing a lot and he taunts me and then puts them blame on me when he gets the reaction he wanted. Anyways. We've been going through hard times and it's both of us. But my gut feeling has been telling me something is off. He got 3 texts on his way to work (3 am) and he said because he got a phone update and it restarted. Those messages popped up again but he said he read them before the update. Meaning they wouldn't pop up unless they were on unread ( we have the same phone. Anyways. I was doing laundry and I noticed subtle white stains on his briefs . They were white or clear. It wasn't many and it was just a bit on the outside. I let it go. Then when we finally had the chance to be intimate. He basically teased me and then made an excuse and tried to talk about our toddler. Then he said he'd rather cuddle when I was touching him and then he said he isn't in the mood and at first it seemed like a job but he was serious. But he was aroused. He just didn't want to have sex with me but made it seem like it and he even commented on it etc before we got to bed. So then I let it go. But then he asked me to wash more clothes for tomorrow and a another stain . Again subtle but this time white and on the inside and a little on the outside. Not a lot . Just wondering. What is it ? Is it sweat? I just don't get what it could be. And I hope it isn't what I think it is. And if it is. Maybe it's not cheating and there's a logical explanation. I was thinking maybe I could get a male perspective before I saw anything dumb