Connection between s** and mentality

Im 20 and im going out with a 30 years old man. we started going out since a year ago and everything was great. i love him so much and yeah we seem to have great chemistry. we've been having great s** for about 6 months now but here's the issue. for the past 1-2 month he has a problem maintaining an erection during s**. we are both attractive sexually so i dont think there's a problem coming from that.

and this is getting complicated since he had trouble getting hard in the first place for the last 2 weeks. we aroused each other before s** and he always said he's very h**** but i cant see any erection.

im not saying that im not satisfied. actually yeah im disapointed , but i love him so much i dont want this to be his burden. he seems to be in pressure and stressed everytime he's incapable of getting hard.

when i asked him is it because of me? did i do anything wrong? or something like, is he bored with me, am i less atractive now? this is kinda affecting my confidence as well. he said nothing wrong with me, its just because he smoke

is it because of his age? i asked about how hes been doing lately, is there any problem etc but he said everything is fine.
i read from the internet that when a man thinks about how he should not fail keeping his d*** hard, that is when he is becoming more concerned of it and then it affects his brain ,so he will start losing erection.

i told him not to worry about it since he seems to be stressed and i couldnt do anything. i guess he's just bored with me. at first he's still excited when he see me naked. now he dont. :(

we still love each other