You are sensing red flags. Do not ignore them. I have more than once and this last time sent me over the edge.
First time was with an Rx opiate addict years ago. Same thing, we met online and spoke on the phone. As it got later in the night time talks, speech would slow and slur. Sometimes random words would interject into his conversation. Sometimes he would fall asleep. I did not know the severity of his problems until we met and went out for a few months. He was addicted to and abusing vicodin. He would go from VA to VA and get them refilled more than once a month. He had mental issues that I had excused as being stress from his divorce. Once I opened my eyes further I could see that he was severely mental. He was the closest to schizophrenic that I have ever met. To sum things up I ended up calling his family to tell them that he needed rehab immediately and that I was putting a restaining order out on him if he tried to come around again. They somehow did get him to rehab amd as far as I know he is clean, but still not right in the head. The sister told me that she felt that he had the same mental issues as the mother did (she abused Rx drugs and committed suicide when they were kids) To this day it creeps me out.
The second is the xabf that led me to this site. I was as clueless to alcohol as I was to opiates. He abused alcohol, street opiates, and me.
Do not ignore red flags no matter how lovestruck you may be. They are there to save you from what we have lived.