bf can’t stay hard when putting a condom on?

Warning: extremely long so if you have the patience to read through it, thank you so much 😂😂

So this past weekend, we’ve been trying to have sex for the first time (I’m a virgin and also his first girlfriend/pussy in 8 years). The problem is his dick has mad girth so condom sizing is tricky. We’ve been using Magnums for this reason and once he stops to try and put it on (I’ve tried, too), he goes soft in a matter of seconds and it’s hard for him to get hard again quickly. We’ve even gotten to the point where it went in successfully, not all the way but kind of inside, but he would go soft immediately after that. We’ve tried me on top, him standing up to put it on, putting lube (silicone) on the condom and in my vagina (I’m ridiculously tight) for easier entry. We’ve also tried the female condom and I had mixed feelings about it...after trying to get it in and not succeeding, we threw it in the trash. Going without a condom while I’m not on birth control is obviously not an option.

I’m stuck as to what we should do or buy next. I’m not upset about it because we’ve found the situation humorous so that makes things easier and less stressful. But I just wanna have sex with him already! Lol 😩😩😩 We’re long distance right now because I’m in school for my last semester of college, so we’ll have to try again when he comes back up (thankfully, very soon). I know the time will come eventually when we start to actually have sex so I’m not in a mad dash to get it done lol.