Why can’t my bf get hard for me ?

I hadn’t seen my bf for 5 months because we are in a long distance relationship and we were on vacation for a week. We had sex on the vacation several times but the last two nights he kept saying he was so tired and kinda was avoiding sex. I tried initiating sex the last night before he had to go back to his home country for who knows how long and then he just said “ okay let’s just get this over with “ I think it just slipped out he wasn’t trying to be rude or anything. We tried to have sex in the shower but he couldn’t get hard. So he sat down and I had my ass right in front of him and he was playing with it and still couldn’t get hard. And then he asked me to look away because I think he was trying to focus on something sexual to give him an erection. We ended up not having sex because he couldn’t get it up. Does it sound like he’s not attracted to me or could it really be all from him being tired ?