Dry vagina when about to have sex....

Me (23) and bf (23) have been together 3 years. I have never had any problems with our sex life till recently. I would always get turned on easily and have enough lubrication.
Until recently. Been going on a couple months, I noticed I was dry down there in general and just simply would not get wet for sex. After a bit my general wetness has come back but the moment we go to have sex I instantly dry up. I don't know if I'm mentally thinking it will hurt because I was dry for a but and there was one time it hurt due to it. Its driving me insane, 9/10 we have to use lube now. We will be making out and mentally I feel turned on but then physically I'm not. But 5 mins before we are about to have sex I will feel wet and ready. I'm not sure if it's ruined my feeling horny often as I feel like ots been less frequent. We also recently had relationship problems so dk if that could play itno it. I'm also on Birth control and have been for 5 years, never had any issues with it so don't know if this is a cause because generally I feel wet and I am leading up to sex its the moment we start touching/ penetration I dry up. My bf is so calm and gentle with it if it happens he goes and gets the lube and carries on. Its getting me reallt down tho because I use to get super wet and feel reallt horny but the fact I can't seem to self lubricate now is ruining it for me I don't want to use lube every time.