Suspicious Actions

So, I need to vent ladies. Yesterday I told my s/o I wanted to come over in the am after I did some errands (since I hadn't seen him in a week) & hang out for a few hours. He said he was busy after 1pm, but was free beforehand.
I go over there around 10am & when I get there he said that a friend of his (old lady, that is like his grandma) asked him to come over no later than 12pm to help vacuum. I sucked it up & said "fine, what I really came for will only take about 45 mins anyways" lol! So, afterwards, we get dressed & I said I'll see you at our friend's party later tonight. All good. 
About 30 mins later, I realize I left my house keys on his kitchen table. So, I call him to ask for the alarm code since he didn't lock the door, just set the alarm on. He doesn't answer. Ok then, I knew where the neighbor lives, so I drove on over. I get there & no cars were in the driveway. His or hers. When I'm driving back to his house, he calls me back & I say "hey just wanted the alarm code for my keys... Sorry to interrupt your vacuuming, etc." He played the whole thing off, gave me the code & I told him "Tell Mrs. So and So I say hi" & he says "she says hi back." 
WTF? Why do men lie & Where did he go? So, now I'm wondering what he is hiding from me. Ugh! Any advice would be great y'all. Thanks ❤️